During some tests with the configuration of wifi i found some of the limitations in Kobo Arc.
The Kobo Arc ( my) has a connection stable with the router only on channel 1.
The connection on channels 2 and 3 is unstable while on all the other is impossible.
This might be the reason here some unable to have a good wifi.
As proof you should set the ruter on channel 1 and not automatic.
For developers .
The Kobo receives the signal on all channels but probably only transmits on channel 1 or channel 2.
I can manually set the transmission channel or there is a hardware limitation https://mobileread.cdn.speedyrails.net/i/smilies/confused.gif