Did you checked if Port Forwarding is still enabled?
Did you checked that FQDN is still bounded to your IP? Check if it returns your external IP address, it could be changed with time
dig yourFQDN
Sorry, not familiar with your Router.
Could you please trace it?
- Try to connect to the FQDN with curl
curl -v -k https://FQDN
Check in output of it, is it able to connect? What IP Address is there? - Try to connect directly to your Internal IP to the NC and check if it works:
curl -v -k https://IP - Try to connect directly to your External IP (that you see in a
digcommand) to the NC and check if it works:
curl -v -k https://externalIP - Check in WebServer Logs. Are you hitting WebServer at all and if an error comes.