Ex2 Ultra transmission app port forwarding

Hi everyone! I got 2 Ex2 devices: simple ex2 (with v2 firmware) and ex2 ultra with v5. When I used transmission app on my old ex2, there was a link http://externalIP:9092 (i have port forwarding on my router). Now transmission app is gone somewhere and i don’t know how to get it back so i decided to use transmission on ex2 ultra. When i open transmission web gui from my home net, it shows me path http://internalIP/transmission/web/. This looks like port 80 tcp. But if i forward tcp 80, browser shows me 403 error.
I connected to device via ssh and got file settings.json. It has string “rpc-port”: 9091, but i can’t neither connect nor telnet to this port, even from my home network.

So, what port should i open in my router in order to connect to transmission gui via any browser from internet? Maybe i have to make some additional settings on ex2 ultra?

This is for version 5 firmware, which i can’t install on my ex2. Transmission is working good on ex2 ultra, i am just trying to get access from internet (buy i’ll be glad if i could return transmission on my ex2. I found links for version 5, but can’t find for version 2).

This post in your answer helped me, thank you!

What to do with v2 i don’t know yet, but but this doesn’t apply to this article.