@David-TP I'm sorry that I forgot to attach the screenshot of my modem, but it's the model CH8568LG. To answer your second question: to be honest I don't know. I never payed much attention to it,...

@David-TP If you think that a solution can be found, I'm glad to spend a bit more time. I did some additional tests. I rebooted the DECO system and just after the speed went back to normal. (see...

@David-TP issue remains the same, even after disabling the 2.4Ghz band. Only after a full reboot of the system (all Deco's), the speed is normal again for a while, but decreases back to 80-90Mbps...

@David-TP Please find the lay-out attached. I also tried to use the speeds test from out the DECO app. Same result.

After a reboot, the speed of my deco system can go upto 700 Mbps. However, after a while it drops down again to max. 80-90 Mbps. Using the system as an access point now, but still the same behavior....