I am experiencing a similar issue.
I updated the plugin, added a new client, clicked apply yesterday and I have also lost access to both the server and my vpn tunnels, on both ios and windows. I am currently away so I can't check the actual server. WireGuard connects, gets an ip, and says everything seems correct, but I am not allowed to connect to anything else any more.
It might just be that the server requires a restart but I won't know until later this week.