Remote Access on Raspberry Pi 4 not working

Server Version#:1.17.0.1709
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Hello, I am running on a Raspberry Pi 4 with Raspbian buster. I am cable connect to my router.
I can get remote access to work. I do not have Port forwarding running on my router.
The thing is I have another Plex server, which I am using until I get the Pi working. It’s running Unbuntu and Plex and remote access works fine.
I have turned off the old server, but the remote access didn’t work on the Pi.
Any ideas??
Thanks for your help

Port forwarding is the most reliable stable way to setup remote access.

Setup a port forward.