I have tried all the Telnet commands in server, but they all fail. But from the local machine every command reflect with responses. I haven’t installed or configured a firewall yet, so there are possible issue might be related to my router blocking the connection. However, I’m using the same router for my home computer and mobile devices, and where those same connections are working fine with them.
FYI: I hosted my nextcloud with Akami (Linode).