I think the latest Dev branch has a workflow that will try mDNS first to avoid the issue.
It does, hence why I'm a bit confused as to what could be going on
I just added some additional code to Fermentrack dev branch that causes it to prefer ipv4 addresses over ipv6 on networks that assign both. I have no idea if this is likely to be an issue, but it's the only other thing I can think of that might be going on here.