How to organize dynamic IPTV relaying to your network?

Question

Video broadcast

There is a media set-top box that is fed with an iptv playlist (http and rtmp links to streams). The problem is that most of the channels have become unavailable outside of Russia. I have a separate computer that is used as a server/video storage. The idea is to set up a VPN to Russia on the server and use some software to direct the desired iptv stream to the network. It is required that these streams automatically change depending on the channel requested on the set-top box.
It turns out something like this:
- On the set-top box, a special playlist of the form http://server:port/IPTV-link
is created - On the server, the software receives such a connection and, receiving a stream from the Internet via this IPTV-link, relays it to the network. If you select a new "channel" on the set-top box with the addresshttp://server:port/IPTV-link-2, then starts rebroadcasting a new stream from the IPTV-link-2 address.
I found a discussion on relaying certain streams to the network, but in this case it is necessary to switch dynamically on request.
Suitable solutions for both niks and windows. Thank you.