Remote Linux server not accessible from same gateway after somedays

Hello,

We are working on Client's remote server and accessing the same from putty from our office.
Now from last 1 month we are facing an issue of inaccessibility of servers from same gateway we configured on our Desktop.

However some machines are accessing the same remote server from same gateway some are not and having error "Server unexpectedly closed network connection"

Then user switched to another gateway which we have as backup. But after some days again remote server stop accessible from this new gateway.

We have Gateways on Linux servers.

I am not able to figure out this issue and need help on the same.

Thanks in advance...

Check the remote server's /var/log/messages for the connection refusal reason by accessing it from some other machine where you have access. Do a traceroute also..

Below is the error i got on the server which is not accessible. But it seems that this is not related to this issue.

Apr 25 03:41:56 qa.xxxxxxx.com autossh[3183]: ssh exited with error status 255; restarting ssh
Apr 25 03:51:56 qa.xxxxxxx.com autossh[3183]: starting ssh (count 2248)
Apr 25 03:51:56 qa.xxxxxxx.com autossh[3183]: ssh child pid is 9658
Apr 25 03:51:56 qa.xxxxxxx autossh[3183]: ssh exited with error status 255; restarting ssh
Apr 25 04:01:56 qa.xxxxxxx autossh[3183]: starting ssh (count 2249)
Apr 25 04:01:56 qa.xxxxxxx autossh[3183]: ssh child pid is 11252
Apr 25 04:01:56 qa.xxxxxxx autossh[3183]: ssh exited with error status 255; restarting ssh
Apr 25 04:11:56 qa.xxxxxxx autossh[3183]: starting ssh (count 2250)
Apr 25 04:11:56 qa.xxxxxxx autossh[3183]: ssh child pid is 12086
Apr 25 04:11:56 qa.xxxxxxx autossh[3183]: ssh exited with error status 255; restarting ssh
Apr 25 04:21:56 qa.xxxxxxx autossh[3183]: starting ssh (count 2251)
Apr 25 04:21:56 qa.xxxxxxx autossh[3183]: ssh child pid is 13088
Apr 25 04:21:56 qa.xxxxxxx autossh[3183]: ssh exited with error status 255; restarting ssh
Apr 25 04:31:56 qa.xxxxxxx autossh[3183]: starting ssh (count 2252)
Apr 25 04:31:56 qa.xxxxxxx autossh[3183]: ssh child pid is 13815
Apr 25 04:31:56 qa.xxxxxxx autossh[3183]: ssh exited with error status 255; restarting ssh
Apr 25 04:41:56 qa.xxxxxxx autossh[3183]: starting ssh (count 2253)
Apr 25 04:41:56 qa.xxxxxxx autossh[3183]: ssh child pid is 14497
Apr 25 04:41:56 qa.xxxxxxx autossh[3183]: ssh exited with error status 255; restarting ssh

Also traceroute to my gateways is working fine.

Please let know how should i figure this out.

Thanks in advance.