How to configure such routing?

Question

Apache HTTP Server

There is a server with a white ip on ubuntu. It has a vpn server (pptp).
In the form of a client, it clings to a windows machine with apache.CGI scripts on a python. The site hangs there. The Windows machine behind the router's nat.
That is, when users go to the ubuntu server, they get to a site that is running on a windows machine. Accordingly, all python scripts knock on the Internet from the ubuntu server ip.
How to make scripts go to the Internet bypassing vpn. that is, from the ip of the router.
Thanks in advance.
Tried to draw.

Answer 1

Instruct pptp client not to prescribe the default route.

Answer 2

Yes, I'll try to guess.
On Ubuntu, port forwarding 80 (443 is optional) is organized on a Windows machine. The traffic goes through PPTP.
In other words, the scheme is as follows
User -> Ubuntu -> (port-forwarding to the tunnel here) -> Windows machine -> Apache
(scripts do something there)
Apache -> Windows machine -> (data is returned to where it came from) - > Ubuntu -> (returns data on request) -> User
Am I correct? It’s just that the network picture is not clear from your question.
And in the end you want such a scheme
User -> Ubuntu -> (here port-forwarding to the tunnel) -> Windows machine -> Apache
(scripts do something there)
Apache -> Windows machine - > User
Of course, I'm not a network engineer, but wouldn't there be jambs if the request went to one server, and the answer came from another?
In general, more specifics.

Answer 3

1. On the Windows server, disable the use of the pptp client as the default gateway
2. On the Windows server, use its own Internet access as the default gateway
3. On the Windows server, for the subnet or subnets to which pptp clients belong, register static route through pptp server.