SUCCESS! I've fixed the problem on a 2012r2 Essentials and a 2016 Essentials. MichaelJordan-7542 in one of his posts suggested to go here: https://blogs.msmvps.com/bradley/2021/04/01/essentials-servers-fix-up-to-get-remotewebaccess-renewed/
Once there, look for "The attached TXT file needs" RIght-click on the word "TXT" and open it in a new tab. Copy the Regedit code. Go to your server and Export the contents of Regedit to a file to back it up. Take the copied code and paste it into a .txt file and save it. Rename the file to your_name.reg and execute it. You will get confirmation it was added. Reboot the server. Once it's up start up the Dashboard and go to Anywhere Access. I tried the "Repair" option and it fixed a few errors, but not the certificate. Then go to Setup and pick "Use another Domain Name", then "I want to use a domain name I alread own". Enter your existing Domain Name. You will have to enter your credentials, let it run and it's fixed!