Hi @peterhaap !
Do you have 'mac-vlan' or 'protocol-vlan' configured? Try to parse the current-configuration and check for those keywords, these are two features that can have similar symptoms.
Are you sure that you do not have some kind of management system that periodically scans the switch' configuration and if it detects the change it pushes old config to the switch? Check the logbuffer with 'display logbuffer' command and track what happens between port manual config and reverting the configuration back. Check for any Telnet/SSH logins, configuration change messages etc.
Another possibility - cluster. I don't have much of experience with it, so I am not 100% sure if it can cause such symptoms, but it's worth to be checked - search for 'cluster', 'ndp', ntdp'
Hi @peterhaap
Just with curiosity I would like to know as what happens to the configuration on the port if you connect a PC instead of a router. Does the configuraiton still change? can you share the full configuration of the switch, and the router.
I am an HPE Employee
Hmm, that is not something I would expect from this switch, to be honest. And I can't recall any feature in Comware 5 that can revert port to hybrid. Technically hybrid with pvid 40 and untagged vlan 40 is absolutely the same as vlan 40 access port with one exception - vlan 1 tagged will be accepted on such port too.
I have searched through the release notes of latest s/w version for this switch and couldn't find any bugfix similar to this, but maybe s/w update is something that we need to try. The latest version is R2222P11, you can download it here.
Could you post your full 'current-configuration' here as well as 'display version' output? Also, while the router is connected please collect output from "display lldp neighbor-information", let's check if the router advertises anything over LLDP that can trigger voice vlan or something else... Let's see if we do not miss anything. Also, have you tried what @drk787 has suggested - connect a PC instead of a router? And another question - does the change from access to hybrid happens only when you connect the device to this port? Maybe it will switch after some time even without connecting the router?
Yeah, such a mistery... Could you post your full 'current-configuration' ? Of course you can delete all non-private IPs, password hashes etc - these won't be needed, but I'd like to see the complete picture. You can send it as direct private message to me.
So, very interesting - connecting router converts the port, but PC connected to the same port doesn't change anything in the port's configuration. If we would be in the Cisco world, I'd say "Blame DTP", but I didn't hear of anything like dynamic trunking protocol in those old switches, but your software is from 09-Dec-2011 so I am not sure if it wasn't some weird 3Com's legacy... I need to check old docs for those versions. Also, keep in mind one Comware specific - bugfixes listed in the release notes documents are not all the bugs fixed. We mention only CFI (Customer-Found Issues), but bugs discovered during internal tests never mentioned there. So chances are there was a bug like this triggered by some protocol that your router is broadcasting out of its port, that bug could be discovered internally and fixed silently.
BTW, you say "display lldp neighbor-information now shows nothing while before it showed the info of the switch connected on the other end op the router." Let's clarify this - does it mean that the router is not connected directly to the 5120, but there is another switch between them? If there is a switch, could you let me know if it's HPE or Aruba or something 3rd party?