I have a nextcloud server (Nextcloud VM installed within a Kubuntu 18.04 host) that has unexpectedly stopped accepting external connections.
Pinging from an external IP works just fine so I don't think this is an DNS issue. I can access the server from the internal IP as well. But from an external IP address I get the error: "This site can't be reached. example.com unexpectedly closed the connection" when using Chrome.
I confirmed that ports 443 and 80 are forwarded using
yougetsignal.com and my router is forwarding those ports to the server. My ip address is not static so I am using dyndns, but I have updated the IP address in the dyndns system manually without resolution to the problem.
This is my first server and I have run out of troubleshooting ideas. How can I fix this problem?