It’s been some time I can’t figure out why my home server cannot be accessed locally but working externally.

Part of the need to ssh locally is because my home server is running on an old faithful IBM X40 with a malfunctioned screen.

Every attempt to ssh locally is futile as terminal will display “SSH: connect to host 192.168.x.x port 22: Operation timed out”.

At first I thought it is caused by misconfigured iptables, but google gives no much hint in resolving. On second thought, I thought newer Ubuntu come with some funny configurations to prevent communication between local computers. Oh well, I come close.

Solution, I found out that my router has enabled a feature known as “user isolation”. It blocks all connections among local computers :)

Happy SSH-ing!