Just checking if I may be able to fix this issue otherwise than by changing the main board to my main robot.
This robot has 2 V4 boards (+ 1 V3 that serves only to put everything on standby by controlling a simple relay).
One of the 2 V4 boards will simply not be able to get a stable IP address. Since I use 2 DHCP routers which serve onto the same subnet (but different range of addresses) in order to handle all my devices (40...), I first thought there was some mess with my network configuration so, before I left to Europe for 2 weeks, on Monday I tried pretty much everything, as far as connecting the board to a lone router, totally separated from my network. I reset the board's settings several times, AP mode will work, although not very stable, EZbuilder would lose connection fast and I'd have to power cycle the board each time. This is actually what the first symptoms back when client mode would work : it would disconnect and require power cycling to reconnect, until it would not get any IP at all, although I hear the successful connection audio message, each time.
Let me know if this has happened to any of you and if you found out what caused it. The only thing I didn't try is disconnecting all wires because last time I did that it took me far too long to reconnect everything so this would be a last resort solution, and I'd probably change the board.
It is really weird: successful connection in client mode to the router, but no IP and the router, would actually see its mac address without being able to assign an IP (which can be seen in the mac filter list).