1 this forum isn't for Gog... most of this forum is Steam users
2 I use Gog Galaxy in Australia to play Bg3 against my mate in NY without issue so its going to be a network i.e, your pal uses a VPN or you just don't have the ping
if you or you pal has changed the email address contected to Larian then yes this error is in their new server trying to 'valid' the old email... yes even if you fulled out all their forms and yes they are well aware of that being their fuckup
however as i said this is prob your netwaork... one question, you say both are Windows, is that both W10 or W11? i.e, are you both on the same Windows build