You should try it like this...
In the first Tenda, go in the settings and set the WAN port to be in Automatic IP i.e. DHCP (& Nat) mode, it may be pre-set that way anyway.
Then, disconnect all cables from all the Tenda's and switch off and unplug ithem Then, put the VM Hub into modem mode
and wait for the base light to turn magenta/purple (on a Hub3 - but not on a Hub4!).
Once it’s in modem mode, the VM hub “MUST” then be powered off. Switch your first Tenda on and make sure it’s fully initialised (leave 5 min) and then put in the ethernet cable from its WAN port to the VM hub (any port will work).
NOW… power up the VM hub and wait 5-10 minutes for The Hub to initialise and and you should get a connection. Use the recommended App to connect the other Mesh units to the first one. This order only needs to be done the first time you connect the router to the VM hub.
I do not work for VM. My services: HD TV on VIP (+ Sky Sports & Movies & BT sport), x3 V6 boxes (1 wired, 1 WiFi, 1 on PA) Hub5 in modem mode with Apple Airport Extreme Router +2 Airport Express's. On 250Mbps, Talk Anytime Phone, x2 Mobile SIM only iPhones.