@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...

@JoseManuel22 Follow this thread for suggestion how to solve your issue, however TL-WR740N is an EoL (End of Life) device - its latest FW release is from 2015 - here. While it's a good idea to update...

@Gumbofizz The only option except other router is to wait for a new FW release, but no one can tell you when that's going to happen or even if it will happen at all.

@tontze Are you using AXE75 in access point mode ? This option should be there when the AXE75 is in wireless router mode.