Can't host servers or use remote access

I'm having a major issue I can't seem to figure out. I'd like to be able to host some servers and be able to use the remote access feature but I'm not able to. Hope someone here could help. Here's my setup.

LTE Hotspot (tethered USB) > RT-N56U stock firmware > RT-N66U TomatoUSB (plugged into LAN)

I've read that having multiple NATs can cause this issue. Since the phone already has NAT, would I need to disable NAT on both routers? I've also read that some sort of port forwarding needs...

Can't host servers or use remote access