SIP Configuration Host Unavailable Error

I installed asterisk 16 in my Ubuntu OS which is Guest OS on my machine.
After installation, I am trying to test so for that I follow https://wiki.asterisk.org/wiki/display/AST/Creating+SIP+Accounts
this link but In this host IP is created statically and also its work but at the time – Execute command I got some error but that’s not my concern right now.
But my main concern is I Create SIP account, then register to that but for register, I am using Softphone but I can’t registering.
Also in some Softphone, I getting UDP port error.

Thank you,

I know there are lots of questions in one post but all are interconnected so I thought its easy to link everything.