*** ALARM connection-failure: Failed to authenticate towards device R2-30: SSH subsystem not supported

[adudek]

Anyone seen these errors pop up even if NCS is able to connected?

This happens every now and then when pushing new config or if our service guarantor is logging to verify the config.

But then it goes away

[rogaglia]

You may have a problem with the number of TTY supported in the device. Check the NED traces to verify.

If the problem is caused by NSO (I meant that NSO is openning too many sessions towards the device in parallel), there will be a new feature in NSO5.5 to limit the total number of sessions NSO can open towards one device.

If the problem is not NSO opening too many sessions towards the device and you cannot solve the problem in the device, one option is to move to commit-queues where NSO will re-try until it gets a free TTY.