I think it is dead. No one bothers posting here anymore. Which is a bugger, because my peers have started connecting through the relay server for some reason, and I don't know why or how to fix it.
I appear to have a similar problem at this point, suddenly stopped syncing. Haven't been able to troubleshoot with other end yet though. v2.6.1 at my end.
Also "Unable to contact the Resilio Sync update server"
I chose to upgrade also: the uninstall failed with a pop-up, the new install failed silently, and an install from the downloaded installer lost all my folders.