$ sudo su
# telnet 80
Trying 0.0.0.80...
1. You are using telnet wrong: it should be "telnet [host] [port]". Please read "man telnet".
2. You do not need sudo to use telnet, do not do that
3. You should also check that Apache is running and listening to this port, use ``ss -lt``.
For this command you _may_ use sudo to get process names (``sudo ss -ltp``). Read ``ss --help``
If you were able to connect on this host, then try to connect to this machine from outside using public IP