Remote access issues

Hi everyone,
New to the forum and Home assistant and a bit of a noob. I am unable to get remote access working. I have Nabu Casa and have selected remote access but still does not work. On reading the home assistant info page, Remote access for Home Assistant, it states that having an IP begging with 192.168 means that you have a private IP space and it it will not work. How to I get round this? I have a TP link deco mesh system and have tried to set up port forwarding in the deco app but I am unsure of the port numbers. I am well out of my skill set and am wondering if I am on the right path. I am under the impression the internal and external ports should be the same and should be 8123 but it will not except 8123 as the external port? Any ideas? Thanks in advance.

It should be quite simple. 8123 is port where HA responds to, so first port forward 8123 to your computer where HA is running on. For example 192.168.1.10 (example)

https://www.tp-link.com/nl/support/faq/1797/

Then find out your public IP adres: https://www.whatismyip.com/

Then on a phone with a data plan, turn off the wifi and visit your external IP

http://IP_FROM_WHATISMYIP:8123

It should show you the home assistant login page.