Here is a snippit of the remoteaccess.log if that helps.  How do I find out what is interrupting  the SSH connection?
[09/09/2021-14:11:41] WARNING Listen socket error/hup - 3, 0
[09/09/2021-14:11:41] INFO  SSH connection interrupted
[09/09/2021-14:12:58] INFO  Next time for retry
[09/09/2021-14:12:58] INFO  Updating remote connection config from server
[09/09/2021-14:12:58] INFO  Making request to https://tunnel.msadmin.macrium.com
[09/09/2021-14:12:58] INFO  internet POST request - url https://tunnel.msadmin.macrium.com, type 2
[09/09/2021-14:12:58] INFO  POST Attempt libcurl: https://tunnel.msadmin.macrium.com
[09/09/2021-14:12:59] INFO  Request success
[09/09/2021-14:12:59] INFO  Connection to [email protected]:1004 (redirect port 4755) requested
[09/09/2021-14:12:59] INFO  MultiSite https://XXXXXXXX.ms.macrium.com | sidebarr uses this Site
[09/09/2021-14:12:59] INFO  Starting SSH tunnel forwarding
[09/09/2021-14:12:59] INFO  Attempting to open socket to 40.84.156.200:1004
[09/09/2021-14:12:59] INFO  trying IP4 address 40.84.156.200
[09/09/2021-14:13:04] INFO  Starting new forward 000000000723E140
[09/09/2021-14:13:05] INFO  Closing forward 000000000723E140
[09/09/2021-14:13:05] INFO  Starting new forward 000000000723DE70
[09/09/2021-14:13:05] INFO  Starting new forward 000000000723E6E0
[09/09/2021-14:13:05] INFO  Starting new forward 000000000723E410
[09/09/2021-14:13:06] INFO  Starting new forward 000000000723D8D0
[09/09/2021-14:13:06] INFO  Closing forward 000000000723E6E0
[09/09/2021-14:13:06] INFO  Starting new forward 000000000723DBA0
[09/09/2021-14:13:06] INFO  Closing forward 000000000723DE70
[09/09/2021-14:13:06] INFO  Closing forward 000000000723E410
[09/09/2021-14:13:07] INFO  Closing forward 000000000723D8D0
[09/09/2021-14:13:07] INFO  Closing forward 000000000723DBA0
[09/09/2021-14:15:38] INFO  Starting new forward 000000000723C7F0
[09/09/2021-14:15:39] INFO  Starting new forward 000000000723CAC0
[09/09/2021-14:15:39] INFO  Starting new forward 000000000723CD90
[09/09/2021-14:15:39] INFO  Starting new forward 000000000723C520
[09/09/2021-14:15:39] INFO  Closing forward 000000000723C7F0
[09/09/2021-14:15:39] INFO  Starting new forward 000000000723D060
[09/09/2021-14:15:39] INFO  Starting new forward 000000000723D330
[09/09/2021-14:15:40] INFO  Closing forward 000000000723CAC0
[09/09/2021-14:15:40] INFO  Closing forward 000000000723CD90
[09/09/2021-14:15:40] INFO  Closing forward 000000000723C520
[09/09/2021-14:15:40] INFO  Closing forward 000000000723D060
[09/09/2021-14:15:40] INFO  Closing forward 000000000723D330
[09/09/2021-14:22:55] INFO  Starting new forward 000000000723D600
[09/09/2021-14:22:56] INFO  Starting new forward 000000000723E9B0
[09/09/2021-14:22:56] INFO  Starting new forward 000000000723EC80
[09/09/2021-14:22:56] INFO  Starting new forward 000000000723EF50
[09/09/2021-14:22:56] INFO  Starting new forward 000000000723F4F0
[09/09/2021-14:22:56] INFO  Closing forward 000000000723D600
[09/09/2021-14:22:56] INFO  Starting new forward 000000000723F220
[09/09/2021-14:22:57] INFO  Closing forward 000000000723EF50
[09/09/2021-14:22:57] INFO  Closing forward 000000000723F220
[09/09/2021-14:22:57] INFO  Closing forward 000000000723EC80
[09/09/2021-14:22:57] INFO  Closing forward 000000000723E9B0
[09/09/2021-14:22:57] INFO  Closing forward 000000000723F4F0
[09/09/2021-14:30:06] INFO  Starting new forward 000000000723FD60
[09/09/2021-14:30:07] INFO  Starting new forward 000000000723FA90
[09/09/2021-14:30:07] INFO  Starting new forward 000000000723F7C0
[09/09/2021-14:30:07] INFO  Starting new forward 0000000006160A50
[09/09/2021-14:30:07] INFO  Closing forward 000000000723FD60
[09/09/2021-14:30:07] INFO  Starting new forward 0000000006160D20
[09/09/2021-14:30:07] INFO  Starting new forward 0000000006160FF0
[09/09/2021-14:30:07] INFO  Closing forward 0000000006160FF0
[09/09/2021-14:30:07] INFO  Closing forward 000000000723FA90
[09/09/2021-14:30:08] INFO  Closing forward 000000000723F7C0

I'm missing some of the context of the problem, but this looks like a normal disconnect - looking at the code, the 3, 0 here means that the socket connecting the Site Manager to MultiSite closed with an error (3 - is POLLERR | POLLHUP from the Windows API), but Windows did not indicate a specific error code. This could be a network disconnection at any level, unfortunately there are no additional clues as to why in this log. 
The short delay before reconnecting is due to some rate-limiting between the Site Manager server and MultiSite to prevent clients flooding the server on errors. It looks like after the connection is re-established, the connection stays up for at least 17 minutes and the end of the log.
I'd recommend you get in touch with our support team for this one - as there's no obvious reason why the drop happens, it could be anything from a momentarily dropped internet connection to some NAT routing that needs a config tweak. Our team should be able to look over the full logs and advise.

Kind Regards,

Alex

Macrium Development

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Thanks for the quick response.   I will investigate the network dropping.