forum post with the same problem: https://forum.vyos.io/t/vyos-1-2-traffic-policy-shaper-match-interface-not-working/8389

exmaple test with shaper policy:

Implemented handling for the CLI command to set a filter by interface(rt_iif).
Implemented a command such as set qos policy limiter test class 10 match test_match interface 'eth1' to generate filters similar to those used in VyOS 1.3.

Upon review, I don't think that this is still an issue any longer in the current rolling release. When saving the config, the effective/running config tree is fetched instead of the session config, and so the incomplete session configuration is not written to disk. The vyatta-bash package also provides a "Warning: you have uncommitted changes that will not be saved." message now when the session has non-committed configuration.

This is not valid for 1.4 and 1.5
Only valid for 1.3 and older images.

https://github.com/vyos/vyos-1x/pull/4187

Thank you, this is my first actual contribution so please feel free let me know if this approach isn't the way you want to do it. If you point me in the right direction, I will implement it however you suggest. I mostly searched the source for other situations where VyOS asks this type of question and copied the idea.

Hey @insignia96
Give it a try and come back if you have questions or doubts
@Viacheslav @dmbaturin can you take a look and suggest if the approach suggested by @insignia96 is ok?

If this could be assigned to me, I am working on a patch that will prompt with ask_yes_no when session_changed() is true of the config, warning the user that the configuration has uncommitted changes and saving it may result in failure to load config on boot.

Thanks for bringing this to our attention @paulywog

I was able to update my router to VyOS 1.5-rolling-202411070006 and my xen vif interface is working once again. Thanks everyone!

the PR
https://github.com/vyos/vyos-1x/pull/4186

I've just encountered the same issue upgrading from a 1.5 build from May 2024 to the most recent a few days ago. Had very little time to investigate. Next week I'll take some more time and will report back if I find anything interesting.