1) Plex does not load on my Browser but works on incognito mode

This is a known issue with plex it is caused by your broswer not letting go of old plex servers

Fix

1) Shutdown/exit/close all Chrome windows/instances,

2) Find the location of your Chrome profile: https://www.howtogeek.com/255653/how-to-find-your-chrome-profile-folder-on-windows-mac-and-linux/ 2 This can also be accomplished by visiting the URI chrome://version and checking for the “Profile Path:”,

3) Move the profile folder somewhere out of the way (or delete it if you really don’t care about having a backup),

4) Open Chrome and complete initial setup.

And that’s it! If you have sync setup, it will automatically restore all synced content…

2) My plex is freezing on playback

This can be a hard one to pinpoint but in short it is caused by your home download speed, If your trying to watch a say a 4k movie this can need your download speed at home to be 80Mbps or more,

If you can not download this fast or the peering is off your seedbox will transcode the file using the servers cpu to Downgrade the stream for you to watch it.

You can adjust the setting on the movie to 1080 or 720p and this should stop the freezing, 

long term The best thing you can do is download 720 or 1080p files. As we can not control your home speeds or the peering to you 

Also please check out this plex guide https://forums.plex.tv/t/info-plex-4k-transcoding-and-you-aka-the-rules-of-4k/378203

https://support.plex.tv/articles/205002628-why-do-i-get-the-this-server-is-not-powerful-enough-to-convert-video-message/

you also need to make sure your using direct streaming see https://www.youtube.com/watch?v=h1XKv8-RNwU