Cannot connect as Wireless Device or to Content Server

[DavidGB]

After two days trying to figure this out I'm completely stuck. (Sadly, since becoming disabled and permanently medicated, I can't think clearly, keep forgetting what I was trying to do, and now often miss the blindingly obvious.)

Back in 2017, when I finally gave in and bought a (cheap) android smartphone, I also bought Calibre Companion and FBReader Premium - really just as a backup as I've been using a Kindle to read on for years, with Calibre on my PC to organize my ebooks and convert formats etc, connecting to the Kindle with a USB cable. Both CC and FBReader connected via WiFi to the Calibre server on my then laptop (2010 vintage Windows 7) easily and without any problems, and CC also connected easily as a wireless device.

Last summer I bought a new Windows 10 laptop, and despite my worries beforehand, both CC and FBReader connected to Calibre on the new laptop without issue. The last time I had reason to connect was 5th Feb.

Two days ago I bought a new Android Phone (Alcatel 3V). Setting up and transferring things has otherwise gone well, except CC won't connect with Calibre, either as a wireless device or to the content server. Neither will FBReader. And when I eventually picked up the old phone and tried on that, intending to check the settings on it, i found that CC and FBreader on the old phone now won't connect to Calibre on the laptop either, whether to the content server or as wireless device.

Now, I think the fact that FBReader is affected too means it's not an issue with CC. And the fact that CC on the old Marshmallow phone now isn't connecting too means it's not an issue with the new phone being Oreo (8.0). I haven't changed any settings in my laptop Firewall and Antivirus (Comodo Internet Security Premium 11), and there are no messages in Comods's logs about any incidents connected with the CC to Calibre connection attempts (it just shows the incoming connections to Calibre being allowed through, but no outgoing replies), and I've always had Calibre as a 'trusted' app.

The only 'big' change on my laptop since Feb 5th and now is that it finally got the big delayed Windows 10 'October update' later in Fenruary - but I didn't see anywhere that that would - or even might - create problems of this kind.

Symptoms:

Attempts to connect as wireless device just produce the white rectangle with 'Wireless device connection' in it and the spinning circle, until it gives up and goes to a 'Failed to connect' screen.

Attempts to connect to the Content Server actually appear to show an initial success, with 'Trying to connect to the content server ...' at the top of an otherwise blank page giving way to 'Index of content server' - but the rest of the page stays blank, and after a few seconds I get a 'Content Server not running' screen.

I get the same results with the default automatic connection settings, and after configuring wireless device and content server connections manually to the IP address of the laptop and the 8080/9090 ports. (And just to be clear - I HAVE started the content server and wireless device connection in Calibre on the laptop.)

Things I've looked at:

It's not SSID isolation - that is and always has been turned off in my router.

No other devices are connected via USB. The only other USB items plugged in are two HDDs, but I tried unplugging them anyway and it made no difference.

In the Calibre server logs, lines to do with earlier, successful use start e.g. 192.168.1.7 port-33565 - 05/Feb/2019:17:11:56, but all those to do with these new failures start e.g. 127.0.0.1 port-58637 - 06/Mar/2019:21:35:54. I have no idea why the log lines for the old connections start with the actual IP address of the (old) phone, but all the new attempts from either the new or old phone start with the localhost 127.0.0.1 instead.

Any ideas what the problem might be?

Thanks.

[theducks]

127.0.0.1 is also known as LocalHost

That address is for a single machine only as a way to communicate between apps. It is non-routable.
You can never access that from the outside of the box, because every box has its own LocalHost

I will assume that 192.168.1.7:33565 is your host machine and you set that port number in the calibre Sharing over the net config.

[DavidGB]

Yes, I know that's localhost - I said localhost right before the address in my post. I thought it was indicating that the Calibre server was somehow interpreting the CC connection as coming from localhost rather than the phone so was replying to the wrong place. However, I've now realised I was misinterpreting the Calibre server access log (as I said, my meds leave my mental processes like they are buried in treacle). The many localhost lines were actually logging my testing the server by connecting to it with my browser on the computer (which works). There are no log lines at all showing access by CC (or FBReader) from the phone. Comodo's View Connections window, however, does show the incoming content server and connect as wireless device connection attempts from the phones - Protocol TCP IN, Source the phone's IP address with port numbers up in the 50000s, destination the laptop's IP address with port numbers 8080 (content server) and 9090 (as wireless device), both as displayed in the Calibre Connect/Share dropdown, Bytes in 148 and 222 bytes, Bytes out 0 bytes.

So CC on the phones (both the new one and the old one that was connecting fine back in early February) are trying to connect, it is getting to my laptop and through Comodo, but Calibre server isn't showing any sign of the access in the logs.


192.168.1.7:33565 is NOT my host machine - it was my old phone's IP address and the port number CC chose to use when I made the last successful connection between CC on the old phone and Calibre back in early February. I was quoting it from the Calibre server access log from Feb 5th to show it was working and connecting then, whereas the only access lines in the log now are from localhost when I test the server from the browser on the laptop.

So - the Calibre server receives and responds to connections from localhost, but doesn't appear to register the connections from the phones, despite the internet Connections Monitor showing they are arriving and being allowed through the firewall. Any ideas anyone?

[theducks]

Sorry about the confusion.
Can you ping your phone/tablets from the laptop?
Have you whitelisted Calibre and the calibre-parallel (workers) with comodo? It might be blocking Calibre connections to the outside

[DavidGB]

I can not only ping the phone, with File Manager + on the phone - which I'm just evaluating along with Solid Explorer - I can click for it to be an FTP server on the phone and access the phone's files from the FTP address it provides in a browser on my laptop. And vice versa, with File Explorer + I can set up the laptop as a local network location and view any locations and files on the laptop set to shared, plus any locations and files owned by the user I login as, in File Explorer + on the phone (including the Calibre directory on the laptop - so I could actually just copy everything over to thee phone using File Explorer + ... but I'd like to get the Calibre server and wireless device working, or I'd just have done it with a USB cable yesterday!).

Although I can't seem to convince Solid Explorer to do the same things, for some reason I haven't figured out yet (maybe the same problem as with Calibre?) To access the laptop with File Explorer + I did have to give my laptop username and password. There's nowhere I can see in the CC settings to enter those, though I did find the button to clear them, so presumably if CC needed to send the laptop username and password it would throw up a login box, and it doesn't. (and I never had to all the other times I used CC up to when I last used it working on 5th Feb).

I have whitelisted Calibre and calibre-parallel in Comodo. And Comodo's logs show it reacting to Calibre's antics under the containment module, but ignoring them due to Calibre and Calibre-parallel being trusted. I also tried turning off every Comodo module (antivirus, firewall, auto-containment, HIPS, Viruscope, Website Filtering) but it didn't make any difference. When all modules are on, only the containment event log shows any entries for Calibre at all, and it is always showing that it ignores them as trusted.

Still stuck.

[stumped]

You say that everything worked before the big windows feature update, and not afterward. So the answer is that windows has changed security settings. It tends to do that with each big update.
So you have to go into windows settings, find all the ones that affect sharing files on networks, and set them correctly. I am typing on tablet so I cannot view mine as I type but that is the area you need to focus on. You need to be on a private network with discovery and sharing enabled.. you may also have to use user names and passwords in areas where they were not previously required. Each windows improvement? tightens security and new defaults are hiding the library pc from the phones so they cannot access the server. CC is probably remembering what worked before the windows update, and so it is not asking for new credentials. If you force stop and clear data for the app it should then ask if needed when restarted.
I had similar fun with a new pc which stubbornly would not let my other pcs connect over LAN to see shared folders until I created a new additional user name and password credentials pair. , googled how to erase the old empty credentials and connected with that special pair and not my normal unprotected login. And moved all shared stuff out of c\users\ .... Into other common areas

[DavidGB]

Everything was working for me on 5th Feb. I did the big windows update to W10 1809 on 16th Feb. I started trying to connect to Calibre with CC on my new phone and found the problem with both it and the old phone on 6th March. So it MIGHT be the update, which was within the window for when the problem started - but it's a month wide window.

I have already gone through every setting I can find for security and sharing, but found nothing that make any difference. I am still, as it was before, on a private network with discovery and sharing enabled. I CAN access, from the phone over wifi, those locations and files on my laptop that are set to sharing or are within my user directory, using the 'Remote Locations' feature in File Explorer + which I think is using SMB (it's using port 445) - and that includes the Calibre directory and its contents. So it is not that nothing on my phone can access the laptop. I haven't managed to get Solid Explorer to connect, though, which specifically says 'LAN/SMB'. and it is not just CC that can't connect to Calibre on the laptop - FBReader can't find the server, and trying to access the Calibre server with Chrome on the phone doesn't work either.

Comodo's KillSwitch Network Connections monitor show Calibre listening on ports 8080 and 9090, and my browsers on the laptop can access the server without trouble. There may well be some setting that needs changing, but I just can't find what it is.

[milady133]

Thanks for the tip on the big Windows update changing previous security settings. It might not be my problem, since my phone running Android 5.1 is able to connect as wireless device, but my tablet running Android 6 isn't since maybe about that time. And yes, I already checked they are in the same Wifi network (normal/5G).

[chaley]

Try booting your laptop in safe mode (see section 5.5 this FAQ) then connecting with CC. I will bet dollars to donuts that it will work, which means that some security SW on your laptop is blocking connections.

Some antivirus SW contains anti-bot protection, which translates to blocking anything that tries to connect to software on a computer from outside that computer. Acronis is a prime example -- it breaks close to everything. Malwarebytes often decides that CC is evil because it tries to connect to an "odd" port on the calibre computer. I would not be surprised if Comodo does the same thing.

The difficulty that arises is that "anti-bot" settings are sometimes hidden so deep that no one can find them. This is a problem with Norton and Malwarebytes. In the case of Acronis, I have not yet heard of a way to tell it that calibre and CC are OK. Making this process more "interesting" is that the various AV packages update themselves without saying anything, which makes the "I didn't change anything" claim meaningless. These SW packages change themselves all the time, as does Windows.

In closing and again, please try running in safe mode. That will tell us whether there is an actual problem with your device and CC.

[chaley]

Originally Posted by milady133

Thanks for the tip on the big Windows update changing previous security settings. It might not be my problem, since my phone running Android 5.1 is able to connect as wireless device, but my tablet running Android 6 isn't since maybe about that time. And yes, I already checked they are in the same Wifi network (normal/5G).

If one device can connect but another cannot then it is almost certain that one of three things is true:

• The devices are not using the same WiFi band (2.4GHz vs 5GHz).
• One of the devices is connecting as a guest.
• The network security setup is "unusual"

Unless you have a very specific and unusual network configuration the computer running calibre cannot distinguish between 2 devices. Either both will fail or both will work.

One of the "unusual" configurations would be a firewall that filters by IP address, which could allow one device (one IP address) through but block another. Another is using MAC address filtering, either in the router or the machine running calibre.

[DavidGB]

Sorry for delay in replying. As mentioned, I'm disabled in a way that means I'm only intermittently up to dealing with stuff, and even then only for brief periods.

The good news is that I now have CC on my new phone working with Calibre on the W10 laptop, both as a wireless device and connecting to the content server. The not quite so good news is that I'm still not absolutely sure what the problem was, or exactly what I did that fixed it (or why it fixed it), and am therefore not entirely confident the problem won't reoccur or that I'll be able to fix it again if it does.

I have been sure the problem wasn't CC, and while pinging both ways, network traffic monitors on laptop and phone, and the other successful uses of other servers on the laptop with other devices on the network, including other apps on the same phone, etc, ruled out many things, my deciding to power up my old Windows 7 laptop that hasn't been on since last June when I got the new Windows 10 one, and finding that CC on my new phone immediately successfully connected to the Calibre (3.20 as nothing on the old laptop has been updated since last June) on the old laptop ruled out many more. It also gave me the chance to check that all my security settings in Comodo on the new laptop were still the same as they were on the old one (where i never had any trouble connecting CC on my old phone to Calibre on the old PC, and now CC on the new phone was connecting to it), and they were (not surprising as when I got the new computer I just saved Comodo's settings from the old one and imported them into Comodo on the new one).

And the only indication of where the problem was and what might have fixed it makes absolutely no sense on three grounds.

Still - everything's working now, and has been for a few days, so I'll leave it at that and hope it continues.