Connection errors multiple times a day

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Hello,

I have a client who keeps getting connection errors multiple times a day on multiple workstations.

They only get these on workstations (not on the terminal server). The terminal server, app server and SQL server are all VMs on a host. They are on version 2018 but were getting those on version 2014 too.

I thought it was an environment issue -> switch not working properly or network issue. Their IT team have looked at the network and they do not think it is network related since the users do not have issues with Outlook ...

I ran a dbspy on workstation and this error came up:

The users see this:

Then they have to get out and go back in.

We have run data integrity checks on the db and there is nothing in there. They do daily, weekly and monthly SQL backups. They also have dbcc scheduled regularly on the database in SQL. We did dbdumps too and no errors reported there.

I checked the path and ODBC and they all look OK.

Is there anything that anybody can think of that might cause this please?

Thank you

Prabha