our office is on a VPN connection to our customer's big UNIX servers to provide tech support, and we use telnet client, such as putty or xshell on windows XP&7.
One month before, we changed our ISP from company A to B, and some of us changed our network ipv4 setting's DNS server setting during the switching process,from the default automatically assigned one, to some public one, such as 18.104.22.168, and changed it back.
Now, any machines with its DNS setting touched, can still telnet to client's UNIX machine, but even a "ps -ef" or "ls -l" which may return more than 1 screen of content get stuck there, until over the idle time and closed by remote servers. All clients, such as telnet, putty, xshell all work the same way.
Has anybody experienced that before? And how to settle it?