@David-TP 

Hello, it seems the old deco i was using in the mesh (not the main one) might be the problem. I removed it from the network (created a new one with only the brand new deco) and everything seems to be fine. But it dropped the internet only once since then (the ONU was blinking the green LAN at the time of drop unlike before where the LAN was static with the old mesh). I'll follow the instructions in email if the network drops again and let you know. 

Thank you

  @David-TP 

About your questions

1. The old network was dropping almost 3 to 4 times a day for the last month.

2. No, I'm using a PPPOE connection so when the deco had white lights on it was showing a valid ip but when the router was red there wasn't any. 

3. No, fhe unplugging and plugging the ethernet cable didn't fix the issue.. only when i restarted the router is when the issue was fixed. 

Note that this was all when I had a Brand new deco as my main one connected to my modem and providing net to a switch which is connected with my 2 pc and an old one basically as an extender mesh in my hallway. After creating a new network without the old one everything seems to be working fine. 

Should I try reconnecting the old one (about 2. 5 years old) with mesh and see if the problem occurs? 

Should i follow the instructions on your email or wait to see if the connection drops out again. 

  @David-TP 

Hello, it occurred again, the deco dropped out the internet by showing red light, it was fixed when the router was restarted. Same shown in the modem where the lan was static instead of blinking