@007Bond  I found with my Main that the middle port wasn't working, so I swapped Deco units and assigned Main to a new unit. Now the lower port of the new Main has the same problem as the previous Main and I'm getting a message  "Abnormal WAN port speed" as well. This firmware upgrade has been a disaster. How do I roll it back? 

  @red3dcom It says it cannot be downgraded it was in the upgrade warning. I'm not sure what to do I got things working but if anything burps it takes a dump and goes all down. I had zero issues with my sys before this upgrade so it is 100% the FW. I tried swapping things like you and it works and then later it does not. I think we have to wait for new FW or buy a different brand for now. I don't know if I can live as it is as we all work from home so today was a total loss work day had to take vacation.

  @007Bond I have installed the 1.4.1 firmware, but on a DECO X50 (which is almost the same model). I powered off - the whole network -  including my switches, modem and all decos. Waited 5 minutes. Then brought the switches backup, then my modem, then al 3 decos stating with main deco. 
 

this helped. Everything is working for 4 days straight. 

  @JanRekenaar Thanks I will try this next time as seems its holding for now. Issues seem to be if anything is rebooted or looses power it doesn't recover on its own. So if someone accidentally knocks one of the six units off-line or there's a power failure, it doesn't recover on its own. This system even has a featured to reboot itself every day or every week whatever you set it for and it doesn't recover on its own. So a special procedure like what you're saying is required to get the system back up online. This shouldn't be if you're not home and you're concerned on seeing your security cameras or something important your whole home is off-line until special reboot sequence is performed.

  @David-TP Unfortunately the directions for downgrading the firware are for Windows machine. We're a MacOS network here.  I have things working as long as I don't use the port that doesn't want to work on whatever Deco is made Main. One of my Decos would not let any of its ports work as Main, but is perfectly happy as a satellite with ethernet backhaul and other devices connected to it. I've tried every Deco I have as Main and they all have some problem with that role since the firmware upgrade.

  @red3dcom I'm also on MAC but can try on Windows on my VMware.

  @David-TP I was adding a couple of Tapo S505 switches to my network. As I was adding the second one the entire network crashed. Most devices (wired and wireless) became disconnected. The main Deco lost connection with the internet. The satellite Decos were repeatedly going off and back online. I was finally able to get the system back up by powering down all 3 decos for about 10 minutes. After that while using the Deco app it said to reboot the main deco which I did. It has been stable since then. The Deco app is still slow to update all fields. Version 1.4.1 has something very wrong with it. When are they going to publish a fix???