Copy job - Unstable connection: unable to transmit data

[rboonstra]

Hi All,

Currently I'm having some issues with copy jobs. After a while they fail with an error (it can happen after a day, sometimes a bit longer) :

Error: Unstable connection: unable to transmit data. Agent failed to process method {DataTransfer.BackupText}. Exception from server: Failed to process {Invoke} command Details: An existing connection was forcibly closed by the remote host

Its a copy job between 2 physical Windows 2019 Repo's with ReFS on different locations. The machines have 512GB memory, CPU is not a bottleneck. Machines are identical to each other hardware, firmware and driver
Firmware and drivers have been updated to latest stable version
We thought that mutlichannel SMB was an issue. Management net and data net run over different paths, but are able to contact each other over those paths. Disabled that, it looked promising , but unfortunately jobs started to fail again.

I have a workaround, that is disabling and enabling the data interface once the error start to happen, and the job will run again.
The router between the sites on the data interface is not a firewall signature based solution

Also opened a case [03969121], but could get any wiser/further with that

The strange thing is in this case, I'm able to copy hundreds of GB's and it suddenly stops doing that.

Any ideas?

[Gostev]

Indeed, these types of issues are usually caused by "smart" firewalls that analyze traffic in real time and drop certain "suspicious" packets automatically, which is why it's so random. But you already said this is not the case... which only leaves us with the possibility of some networking equipment misbehaving (router, NICs etc.)