How to fix strange server behavior during port forwarding?

Question

ZyXEL

There is a small office, let's call it "A"
There is a Zyxel keentic start
router Behind the router there is a server on Windows 2008 R2, with the firewall turned off
Ports forwarded from the router to the RDP server + a couple of other ports
On the router there was a sinking 192.168.0.0, changed to 10.1. 100.0, port forwarding rules have been edited.
Actually after that, access to the server was lost from the "selected" IPs.
I tried to connect from 5 places
1) My house, everything is ok, there are no problems.
2) Work, here are the problems, the ports that are forwarded to the server do not respond, RDP does not work at all.
3) Remote client, same problems
4) Another office, everything is ok
5) Familiar, everything is bad.
What does office "A" use the same provider as 1, 2, 4
It was the ports forwarded to the server that stopped working, if you take, for example, port 80 and redirect it not to the server, but, for example, to the IP PBX, then from problematic places access appears on this port, but there is a problem with access to the server!

Answer 1

I read it three times and still didn’t understand anything - who is being thrown at whom and who isn’t working with whom? Write in simple sentences or draw a diagram.