Thanks for getting in touch. The error you are seeing shows a networking problem. We hold a TCP connection open between the Octopus Server and Tentacle and re-use it. The exception you are seeing is thrown when that connection fails.
If it is only occasional and your deployments are still working it isn’t a problem, we reconnect automatically, however yours looks to be every 10 minutes or so. Sometimes customers have a firewall that kills off open connections that are held open, or problems with their networking equipment on that route. Do you have other Tentacles that are working?