Dockerized Fika Error: unexpected end of file

[topaz apex]

Fika Version: Beta 0.9.8892.36315
SPT Version: 3.8.1 (29197-d3ac83e)
Port Forwarded (UPnP enabled);

Explain Problem: Hosting server off a docker container on unraid through a secondary pc (PC B) connected to my local network; Attempting to connect through my desktop pc (PC A) through WAN IP of PC B to test getting into the game and set up before trying to get my friends to download. When attempting to launch game from PC A @ WAN IP of PC B, Error is displayed on server log from PC B (pic attached) from the server on PC B, it shows everything connected in launcher and PC A has no a troubles setting a profile, only when launching game do I have the error.

What have I tried so far:
Note: first time linux/unraid/Docker user so sorry if I'm missing something obvious. friend help me set up unraid but I've had to manage the dockerized fika install, which seems easy enough, I just couldn't find any support articles relating to this specific error.

PC A can run the game fine with server running on PC A base launcher address (127.0.0.1:6969) (player log PC A- attached). I haven't tried to host through fika, but I get the initial pop up. If I try to point the launcher's http address on PC A to PC B's WAN, I connect fine and the profile stores fine; error still shows when launching game (player logs PC B- attached).
I am getting a download file (line of unfamiliar characters) when trying to connect to the WAN IP:Port (of PC B) in PC A's browser. Network wise it seems everything is working accordingly. unless the container is being blocked from downloading something?

Followed UmbraPrior's guide to reinstall this morning after seeing other docker support threads. I've copied the install commands from my end into the txt files incase they help. Also tried to install zlib through "apt-get install zlib1g-dev" in the container console as an attempt to fix things. Appreciate any pointers. Thanks for your time.

[lapis heron]

I see you have a URL in your 'backendip'
is that the same for wanip in your http.json
(i didn't know that worked)

[topaz apex]

so far, i've had it running that way with no issues connecting. friend set everything up as far as NPM reverse proxy and DDNS. i just bought the domain haha. I've been able to connect via the client, PC A, by setting the launcher to the same url as specified in the backend. which i believe is the same as the IP in http.json. i don't want to act like i know what i'm talking about as far as networking goes haha. if i messed up any terminology forgive me.

[topaz apex]

okay that may not work hahaha. I changed PC A & PC B backend IP (http.json) to the LAN IP of PC B (both wired into router), launched fine with no issues on PC A and no errors on PC B. I'll try to find which wan ip to use instead there or maybe I messed up when i tried to set up npm for the container.