I'm also having this issue, client-main.txt just tells me, "Failed retrieving master server list at url https://masterserver.vintagestory.at/api/v1/servers/list". The URL looks right, my firewall settings have been made to allow vintage story to connect through, no VPN on or anything, reinstalled today as well to try to fix it.
Additionally, I can't connect to any server, as the connection is always refused by the target machine, even when windows defender firewall is completely turned off...