Yeah I'll have to look through them and play with the firewall and router. Project zomboid did something very similar but I was able to find a way to make it work with my two custom ports.
Absolute worst case scenario, I create my own MITM to replace the 8888 for the client response lol
I also wouldn't consider this a secret....
I found years ago that if you block ubi.com and ubisoft.com (if you have a self hosted DNS or a way to block domains on a network), and any other sub domains you might spot, the games work fine. They just take like a full minute to load while they try their best to hit the servers. So yeah I've never agreed to the TOS for a few games as a result.
Needles to say, you'll need these domains unblocked to play multiplayer.