Access to IP phone server and router via VPN

[orvieto]

Hello everyone,
This might be well discussed, but I couldn't find it.

I'd like to access the IP phone server and router at the office from home. The person who used to work left without any info. He was able to connect to the phone server (and the Cisco router).

We set up a QNAP server at the office via UPnP.
Here is office info:
Cable internet modem
192.168.1.1 - Cisco small router
192.168.1.50 - Qnap server
192.168.1.250 - IP phone server

Here is how we access via VPN from outside of office:
1) Connect to the office via Windows VPN (WAM IP, User/Pass)
2) Open Windows Explorer and type \\10.0.0.1 (QNAP), you will see all shared folders
3) Double click desired folder, and type User/Pass

When connected I ran Angry IP started from 10.0.0.1, but it couldn't find the phone server nor router.

I don't know why he could access to the server and router???

Please advise.