I am no expert in home hosting but if you are running a lfs dedi on one machine and try to connect with another machine, your client presumably wants to connect to your internet IP address instead of your internal LAN address..
And most routers do not like that... Get very confused...
If you want to know if the dedi is correctly configured you need somebody else 'from the outside' to test. I think.
How to connect internally, I do not know.
It's possible to define an internal IP address in the config though. But hmm..
Yeah, try that