The internet available to me is a shared router that I do not have administrative access to. If really needed I could reset the password but I rather not. I plugged in a network cable and plugged it into the WAN port on my own openwrt/lede router. This gives me a semi-functional but secure network where I have a firewall. However this is a double NAT, which breaks some programs.
What I want:
I want to assign my own network the IP's given from the shared network(192.168.1.0/24) where I keep my firewall enabled. In a way this is similar to assigning public IP's from your ISP to your whole LAN while having a firewall. Simply bridging the WAN and LAN side works but I lose the firewall in this case, which is missing the point. I simply do not trust the other tenants.
Unfortunately my knowledge about how to route networks is limited to NAT so I don't really know how to approach this(sidenote: any good tutorials on routing?). I did find this: https://lede-project.org/docs/user-guide/firewall_configuration#stateful_firewall_without_nat.
But that doesn't work. I simply lose internet from my LAN side when I disable masquerading(which I assume is NAT)