@David-TP 

  @luckystrikes 

Sorry he hasn't responded yet he is the only tp-link staff that takes care of the en forum and he has other jobs on top of that. I Just sent him a message asking him to reply to this post. FYI this is his weekend so it will take at least 24 hours maybe longer before you received a response from him 

Sorry again for the wait. 

  @luckystrikes 

Hi, thank you very much for your time and patience.

For the "AX50" in the topology, is it Archer AX50:https://www.tp-link.com/en/home-networking/wifi-router/archer-ax50/

Would there be any chance that you could adjust the Ethernet Connection a little bit, connecting both Deco X50 units to the same Ethernet switch?

such as:

Even in AP mode, AX50 still has default WAN and LAN ports. Ethernet Backhaul IEEE 1905.1  IGMP packets are confined to a local network, which might be unable to pass through AX50.

Port 20001(UDP) and 20002(TCP) are both used for data communication between the Deco App and Deco hardware.

Thanks a lot.

Wait for your reply.

Best regards.