VERIFIED - if you change your local computer date back to 6-17-2022, you are able to log in and play without the Error 13.
as some have surmised, the issue is most likely a certificate that expired on 6-18-2022. The local game client has a fail-over of Error 13 when it cannot properly connect to the server for login.
if you change the date - you can log in and play. on my third game now.
to change date:
1). Click START (or locate the command prompt application).
2). Right click on the command prompt app and RUN AS administrator.
3). Type the work DATE in the black command prompt box.
4). enter 06/17/2022 and hit ENTER
this changes your local date on the local PC and allows the client to successfully connect and log you into MWO.
To undo this - just follow the directions again and use today's date.
Edited by Warbrynger, 19 June 2022 - 09:36 AM.