This table shows which DrayTek APs are mesh-compatible with which routers.  (Scroll to see more models).

2135AC

2135AX

No mesh feature yet

2765AC

2765AX*

No mesh feature yet – see firmware 4.4.3 has been released March 24

2865AC

2865AX

2866AC

2866AX

2927AC

2927AX

For more information on how to create the mesh system: https://www.draytek.com/support/knowledge-base/5682

Note: .11ax routers will support the mesh feature with the AP906 but not other APs.

* The 2765ax will support the mesh feature with the AP906 in firmware v4.4.3