I have discovered another issue with the RAs sent out by my ER605.

This is the lifetime that I have currently configured:

The router sends RAs every two minutes, which is not often enough because when the lifetime is reached the prefix expires for a short moment causing existing connections to break.

When I change the lifetime, the interval changes as well, so it will always be a little bit too short. :(

The fact that it's taking the valid (and not the preferred) lifetime as the interval also causes another issue: Without another RA, the address becomes deprecated after the preferred lifetime expires and (at least on Linux) is no longer used for connections.

In short, internet stops working whenever the preferred lifetime expires, then after the valid lifetime expires the remaining existing connections break but internet starts working again for a bit (because there was a new RA) until the next time the preferred lifetime expires.

This is completely unusable, I think I'll have to ditch the Omada router for now until this gets fixed. I don't think there is anything I can do about this configuration-wise, (apart from using a really long lifetime, which then breaks when the prefix changes). There seems to be no setting to set the RA interval.