Why does RDP disappear when connecting to the Internet?

Question

System administration

There is a network in which:
RDP - Winserver 2008r2
4 companies that connect to it via RDP
Router that distributes the Internet.
Sometimes computers cannot connect to the server. After turning off the router after about 5 minutes, everything becomes ok. What could be the reason for this? The router changed, I did not find anything interesting in the logs of the router.

Answer 1

Pings to this server in LAN go normally without crashes and big delays? does telnet ip server 3389 happen after rebooting the router is there access to this port?
you can connect the LAN to the switch and the link from the router to the same switch that they normally see each other
in the logs of the PC server ?