Need help! Problems with connection


I have used spark for 2 years and suddenly on the last week it stopped to connect to server.

We have 3 computers in our oficce and they connected to the internet through 1 router via Wi-fi

The problem is: when 1 user connecting to our working server from one computer - it is ok, he is online. But the second user from another computer from our office can’not login, the error is Can not connect to server: invalid name or server not reachable

If user try to connect from another computer placed not in office - it is no problem. It could be 3 users online.

I have checked settings of our IP, firewall - there is no filter to port or blocked connections. NO rules at all.

What could be a problem?

What version of Spark you are using ? You use Openfire ? (version ?)

Spark version 2.5.8 for windows