@xrpixer thanks for submitting. Any change you could double check it on a recent nightly build of VyOs 1.2.x? => https://downloads.vyos.io/?dir=rolling/current/amd64

Sorry for the late response on this.

I checked the nightly build. The error still exists there, but the message is much more clear.

option arp_interval: mode dependency failed, not supported in mode 802.3ad(4)

Ah! This makes sense.
It got me looking at how this should actually work.
arp_interval is used to detected dead links. When using mode 4, this is done using miimon.
Using the two in junction is not possible according to this -
https://www.kernel.org/doc/Documentation/networking/bonding.txt

I did find that if you configure arp monitor and then afterwards configured the mode and hash policy it would actually commit. However, if you look at the underlying config in /sys/class/net/bondx/bonding/arp_interval, it is set back to 0 and miimon is configured.

Anyway, I ran across this when working with bonding to a set of switches. I later got it to work when bonding to a different vendors switches, thus the arp-monitor was never the issue.

Thus, i'm an idiot. haha

Thanks!!

@xrpixer thank you very much for the clarification. Hopefully other users can benefit from it, too.