It looks like the issue is caused by SVN Server file timeout settings.
Editing the “servers” file in:
%AppData%/Subversion
to have the following under “[global]” at the bottom of the file seems to fix the issue.
[global]
http-timeout = 7200
Though now I get an 502 error. If I restart the docker container running scm manager then the pushes work again for awhile, but big pushes seem to get back to having the 502 error after some time. Smaller pushes always seem to work.