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

[james]

ive setup my home mw6 mesh wifi through this guide following method 2 wired backhaul and everything was working fine for months, until recently my smart home devices kept dropping off the connection randomly which i do not know how to solve. i tried restarting the main isp router but doesnt help in most cases, normally i had to restart the primary node so that the whole mesh system would restart all together, but this also does little help. for instance after resetting the smart device A would the be able to connect back to the network but the it would cause smart device B from another location of the house to be offline and unable to connect back to the network. if i get lucky after countless times of restarting the primary node everything gets connected and works well in the house until 1 or 2 days later one of the secondary nodes starts crashing turning red or the whole network crashes leading the whole operation back to the beginning and i have to do this all over again and again which is really frustrating, does anyone experience the same as i am? is there any way to fix this issue? i am using the method 2 wired backhaul by Dave and internet speeds are great, i have 7 mw6 connected throughout the whole house at different locations and 6 of them are secondary nodes connecting to LAN port via network switch.

at first i thought it was the ISP issue and had called them to investigate, they came and check on my internet and said everything was a ok. they recommended me to upgrade the modem and router since it was old to try see whether it resolves the issue that is under ISP company devices just newer models which i agreed and after upgrading they were the same, all tenda's around the house still causing the same issue. my tenda connection is under DHCP setting am i doing anything wrong? how can i solve this issue