You are connecting through the Plex relay and since it does not look like you have a Plex Pass you are limited to 1 Mbps. You need to figure out why your remote access is not directly connecting anymore.
You should be able to disable the option to use the relay, just be aware that means if there is an issue with your remote access you probably won’t be able to access your server outside your network until you get that fixed.
The option to disable the relay is found by clicking the settings button (the wrench icon) then in the left panel click on the “Network” option under your server then scroll down on the right side to almost the end (should be the 4th option from the bottom) and uncheck the box for “Enable Relay” and then click the save changes button.
If you have issues accessing your server remotely after that, you will need to figure out why your remote access is not working.