I bring here some more evidence to prove that the RE650 V1 can support OneMesh, the next images show the RE650 recognizing the backhaul formed by the Router Archer C6 where the OneMesh repeaters will...

@Fool89 It could be some incompatibility of the extender with the switch, try the direct connection with the router. and I'm glad you were able to solve your problem.

@Jacobcr yes you are correct unfortunately because the port is Fast speeds above 100Mbps will be kind of impossible, either using it as a repeater or as an access point, if you want greater search...

@Fool89 could you show me the settings used by your router in the Internet LAN tabs, and in the Wireless part ????

@Fool89 my current network is formed by these devices. The RE650 unfortunately does not enter the OneMesh network but switching between devices until the RE650 works fine even without being in Mesh,...

@Fool89 I'll show you how I configure mine in. If you don't use it in OneMesh, this configuration that I showed in the images is enough for it to work correctly and not give you headaches.