VPN connection through Yota fails?

Question

VPN

Good day to all. The situation is as follows, there is a VPN server on it, the settings cannot be changed. I'm trying to connect to it through a standard Windows VPN client from my computer (Windows 7 Home Premium, Internet via Yota modem (there is no wired and never will be, because the private sector)). As a result, sometimes the connection goes through, but more often it fails with an 800 error . It was noticed that it only works if the modem received an IP address like 188.162.64.11 , 188.162.65.74 etc., and does not work, which is more common if the address is 94.25.229.250 etc.
The question is whether it is possible to somehow get around this problem, because. work is worth it and people are nervous, but going to the office every day is not smiling.