Hoping this will help someone.
I have been using Cloudberry backup for windows server for years and recently updated the software to MSP 360
I began getting a 1003 error, "unable to contact remote server" (using Backblaze B2).
I contacted support but was told I would need to use paid support.
Just by chance I realized the system clock time was wrong on my server
As soon as I set the proper time the backups resumed without error.
I hope this saves someone some time!