1. If you have a mix, and if the Aginet or Tether app or the Web UI does not work, then you can still try the method mentioned in the following TP-Link FAQ. It is also mentioned by
@tsammyc who has done EasyMesh with TP-Link Archer BE230 (main router) + HB710 (mesh node). I have using the method to setup Easymesh with TP-Link Archer BE805 + HB710.
Reference:
https://www.tp-link.com/sg/support/faq/3925/
1) Factory reset the mesh node (also called satellite node, or EasyMesh Agent)
2) Connect mesh node's
LAN port (not WAN port) to the main node LAN port, using Ethernet cable
3) Wait for TP-Link EasyMesh to finish the setup.
4) Unplug the Ethernet cable, power down the mesh node.
5) Put the mesh node to the correct position, say your room LAN port (if using Ethernet Backhaul). You can use WAN or LAN port to connect to the room LAN port in this case, it does not really matter. But I will recommend to use WAN port to connect to avoid confusions. Power up the mesh node and you should be fine.
6) If you do not have LAN ports in the rooms and need to use wireless backhaul, just find a suitable location for the mesh node (which can have good connection to the main node), power up the mesh node and you should be fine.
7) Check EasyMesh configuration in the main router Web UI to make sure EasyMesh works fine.
2. You can also use the WPS button method to see if it works for you or not.
https://www.tp-link.com/sg/support/faq/3581/