routing – Route for one website only

I have two computers, let’s name them A and B, and a device C that provides a web interface to control it.

Device C has to be connected directly to a NIC on computer B. Device C’s web-interface can be accessible over (IP can be changed) and https://device-c/ on computer B. It also runs a DHCP server, so computer B is assigned IP

Computer B is additionally connected the same network as computer A via a separate NIC. Computers A and B get IP addresses and Both computers run Ubuntu Linux (18.04).
Note that, device C should not be attached to this network.

My current solution to access device C’s web-interface on computer A is to open a reverse tunnel with SOCKS proxy, e.g. ssh -D 9999 -f -C -q -N user@computer-B and configure my browser of choice to connect to over localhost:9999 using a dedicated plug-in.

Instead of this browser-specific solution, I would like to configure computer B to also serve as a router to device-c. Only HTTP traffic should be routed.
I’m also fine if device C’s web-interface will be accessed over other address and port, e.g. https://computer-B:8080.
However, it is important that other traffic between Computer A and B is not router to device C.

How to achieve this kind of configuration?