TL;DR, unblock/allow
www.msftncsi.com
Recently I had updated my Kobo to gain a working download option in the web browser..which is key with calibre and the media share server. Upon updating, the browser started to work for downloading and everything was wonderful. Then I went on vacation.
When I came back, my Kobo would not use my WiFi. It would connect but would tell me it was a "hot spot" and pull up an empty login screen. If I cancelled, it would disconnect. If I pressed the X it would disconnect.
I rebooted several times then finally, reluctantly I tried the factory reset. which made matters worse. Because you have to use a pc or WiFi to set the damn thing up and I run Linux, I was now in a situation where I couldn't use the Kobo at all.
I finally tethered to my phone over the LTE connection which got me back up and running, but WiFi was stilled hosed! The Mac address was also wrong when WiFi wasn't connected - it showed a mac address from the wrong vendor. I got the right Mac address by connecting and leaving the empty login screen and checking my wifi routers active list, then got the IP from the dhcpd.leases file and tracked down what it was doing.
It checks for a valid network connection by using a msft URL (
www.msftncsi.com) which is used by windows for checking network connectivity. My local DNS is a pi-hole to block ads which was recently updated and started to block the Microsoft URL.
It is sad to see such a poor design choice made to detect if a network connection is valid. The least it could do is check a URL under the control of the device manufacture. A better approach would be to allow a method to force using the WiFi connection even if the device believes it is a Hot Spot.