@TPGibbon 

Nowhere to check the nat loopback. It's working by default. Do you run into issues with this firmware? 

Hello John234,

thanks for reply. I have this setup: [internet] -> [modem] -> [router1] -> [router2] -> [server]

The problem is, that the [modem] does not support NAT-loopback (when I want to connect to my external IP from internal network, it just does not respond). I cannot get rid of it (it is required to process signal from my provider). So as [router1] I have TL-R605. I would like to set it up so, that when request comes from internal network to my external IP it would redirect it back to my network instead forwarding it to the modem. I have tried setting up the One-To-One NAT but that did not help. I could run my own DNS inside the network but I hoped there will be more elegant solution to this :-/