@heyyoumattyu 

keen to follow this thread or see if TP-Link have an answer. i have exact same issue, i have 3 M5 units in the house. updated to 1.5.1 build 20201022 and since then throughput speeds have ground to a halt

rebooted several times and still same issue

@TP-Link 

1. Would the satellite Decos become red when they failed to connect the main Deco?
Yes, the satellite Deco turns red every 5 minutes or so which didn't use to be a problem. I've swapped Decos to see if a specific unit was the issue but same problem happens especially in peak usage. It doesn't happen at all at night. 
 

2. How are these 3 Decos connected to each other?---it would be highly appreciated that you could provide us a diagram of the Decos and the distance in between?
Main Deco is connected to the router. 1st Satellite Deco is about 5 meters away but with a wall blocking it. 2nd Satellite Deco is 1 floor up but only about 7 meters away from the Main Deco. It has been connected that way for the past 6 months without issue. It only started after the latest update which I did last December 2020.  

Here's more or less a diagram: 

 

3. Have you tried to reset the whole system and set up again to see if that helped?
Yes I've tried to reset every Deco and the entire system but the speeds and the range haven't returned to their original settings.

@heyyoumattyu Hello - did you manage to resolve this problem?  I am having exactly the same problem after exactly the same firmware update.  The setup of my decos is also very similar to yours.

Thanks.

@James723 

hey I resolved my issue with reinstalling the firmware via the web browser and not via the app

@James723 
So far the problem seems to have resolved itself. The major thing I did (and I'm not completely sure if it helped) was to reduce all metal / Bluetooth-emitting devices between the main Deco and the Deco in my room. They might have been interfering with the signal somehow. 

I also did a website-based firmware update though so maybe that helped as well. 

Hi all, how to reinstall the latest firmware when i try to download from website the version available is lower than what i have updated via app?

@eddyyeah 
Hey there, 
can you tell me how to solve the issue.