@FlyingDutchman0 AX20 v1 supports only Onemesh and for building it you can use only a compatible range extender. If your question is "can I use a 802.1a/g device to connect to this mesh network", the...

@monkeykong When WPA3 security is selected the SAE protocol is used - details.

@IVW When in AP mode AX55 (and almost any other router models) LAN ports are available for wired client devices - details.

@tontze If AXE75 is in this mode: you don't have that option. You'll have that option only in wireless router mode.

@Cozz The communication between AX55 Pro and RE450 is more like this: If your RE450 in HW v4 you could configure EasyMesh between the AX55 Pro and RE450.

@JohnV1 This could happen when you have more than one DHCP server on your local network. Do you have any other devices like ISP modem/router, range extender, etc. ? Make sure that you have only one...