Network interface troubleshooting

network link is not coming up after we flap the link with 14 and 16.04.

we tried:
ethtool ethx
#link up and running traffic>
ifdown
ifup
ethtool eth x

#link stays down on server and wont recover expect reboot

BUT switch interface is UP and UP running Tx counters are increments and Rx null. This is the same link one side up and other side is down!

This issue is not consistent, we tested same server week ago and saw issue, not this week!

What we can get in case we see the issue again? tcpdump wont show anything as interface is down and not counters increment.

No physical issue, as happening on different hardware enclosure and works fine after reboot.

Thanks in advance.

I’ve moved this to the Support category because this site isn’t designed to take tech support questions. Sorry. I’d recommend using one of the official support channels listed on the https://community.ubuntu.com/t/finding-help/712 page