After spending a good part of the night resetting everything (router, WiFi extender). I am happy to report a substantial improvement regarding my WiFi situation: 3 hours straight of 24 bit 192KHz and no disconnection! (Of note, I did not have time to listen but at least I did not see any drop yet)
What did I change? I removed the extender (RE7000) that, I believe, used to help a bit with network stability with the previous firmware (it created a wifi network only for 2Go and was 50cm from 2GoH2). Still, this was not good enough to reach the serenity/stability to make it useable.
I have now setup the 2Go to connect the router (linksys EA9500) and reserved an IP for it.
With the firmware update the device may have changed name (and lost the previously reserved IP). Could this explain why my firmware update did not seem so successful? I just really hope this sudden improvement is not due to the bank holiday weekend (resulting in less WiFi interferences).
For those who may be in a similar situation to mine. A symptom I “used to have” was a drop from Roon and no more WiFi network signal in GoFigure (none amongst the three WiFi configured within 2Go had any signal, it looked like they were all out of range).
Of course bitrate is limited to 24bit 192 / DSD128, but at least I have now a message telling me the problem is “the audio file is loading slowly”, so adjusting the max bitrate solves the issue.
So if the WiFi holds, 2Go will be more than enough to me and the rare albums I have above this rate will be on the sd card.
I hope this improvement will last and will help others.