Are you performing the proper WSUS maintenance including but not limited to running the Server Cleanup Wizard (SCW), declining superseded updates, running the SQL Indexing script, etc.?
https://www.ajtek.ca/wsus/how-to-setup-manage-and-maintain-wsus-part-8-wsus-server-maintenance/
I know it's a bit odd asking something that may seem off topic, but approving an update should NOT CAUSE a reset node to happen. This is usually due to lack of maintenance and/or lack of optimization.