How to set up Tenda Nova mesh for wired backhaul - MW5, MW6, etc.

[Dan]

I wonder if Tenda changed something in a recent firmware update that breaks this backhaul method.

You can try the following just to rule out a faulty node or network switch, i.e. try step #1, if the issue returns, try the next step and so on.

1. Move the network leads from each node to different switch ports.  E.g. if they were connected to ports #1, #2, #3, try moving them to #4, #5 and #6. 
   
2. Swap the two secondary nodes.  If the issue issue moves to the other node area, then that one may be faulty.
   
3. Swap a secondary node with the primary node (may require resetting and reconfiguring).  This will rule out the primary node. 
   

If you can get by with two nodes temporarily for a few days, try turning off the secondary node in the least used area.  If the issue does not return after a few days, swap the two secondary nodes.  If the issue returns with one secondary node but not the other, then it's likely a faulty node.

Many thanks you Seán!  I will try this next time I face this issue and update.