I have a router Acrcher C7 and RE505X.
I want a onemesh wifi network.
I was able to sync between them during setup, when the RE505X was connected by wifi. It was registed in the router as ONEMESH device.
After moving the RE505X to the best location for full coverage on the second floor, I connected the RE505X to the ethernet, directly to the first floor to the router.
The RE505X was updated in the operation mode to "Access Point". Since then, it is working fine on the 2nd floor but the problem is that it is not recognized by the router as a onemesh device anymore.
Note: in the past, I performed the same setup with RE305. It worked as a "onemesh" network even that it was connected by wire. I decided to upgrade to RE505X as it has a 1GB ethernet port.