Thanks for touching base with us @Dick_Cooper, sorry to hear that the behavior has reoccurred on your setup.
In light of your most recent report I am going to be enabling diagnostics on your account to help aide in our evaluation of this behavior you are experiencing. What this action will do is the next time Roon is active on your core machine a diagnostics report containing a set of your Roon logs will be automatically/generated uploaded directly to our servers. Once the report comes in I will confirm that it has been received and then swiftly pass it over to our tech team for analysis.
Additionally, since noting that this behavior has reoccurred have you by chance tried testing with the mentioned switch bypassed again to confirm if things stabilize? The reason I ask is because if the switch happens to be “managed” we have seen a few issues crop up with these devices in the past ( Example: #1, #2, #3) and recommending that flow control should be enabled on the device has helped others.
-Eric