Evening all,
We've recently ran through an in-place upgrade of our Cluster servers from 2016 to 2019 Datacenter edition. It all went very smooth and everything seemed to be working.
However - a week later and suddenly the cluster is failing! A validation report shows that the three nodes cannot talk to each other on any cluster network via UDP Port 3343.
I've opened the necessary ports on the firewall, in addition to what HyperV probably adds - but it's still happening. I've restarted the machines - still happening. I've used Telnet on the servers to test they are open - and they are.
This was working fine as 2016 - so something has gone wrong somewhere.
I'd be grateful if anyone could help or offer advice on what to look for.
Thanks
Gareth