Can't Connect My Server

I just purchased a new computer. I have everything connected, but when I launch my Plex it doesn’t connect to my server. I know this is probably a stupid question, but I am not sure what I need to do to locate or reconnect. Thanks for any help.

Start with this - https://support.plex.tv/hc/en-us/articles/204604227-Why-can-t-the-Plex-app-find-or-connect-to-my-Plex-Media-Server-