I've had my home upgraded to a Trooli 300/100 FTTP service. I can sit next to the router and using the wifi get the 300/100 no problem. I hook in my old M4 deco into the router and run a speed test and the maximum up and down is 90/90. I see a lot of posts on here saying the M4 isnt Gigabyte compatible. 

Do i need to ditch the M4 altogether and replace with something else?

@RGaskell 

I think you can bring your router to the support center to check. I did it and they said it's no problem. I check again at home. My m4 found out to be no problem after I changed my M4 power adapter. The problem I've got was using the old Tp-link router's power adapter. 

@jondoe I'm pretty sure I'm using the M4 power adapter. I'll try one of the other ones.

@Imee1976 

Im sure this is manufacture issue because i bought 1set M4 deco with 2 wifi mesh a year before and use 1 at my house and another 1 at my office, since its good i bought another set today and combine it with my old M4, unfortunately the old one still got maximum speed and the new one is capped at 100mbps.

we talk about M4 here not E4

if u think its about cable, I already try exchange both of them and still get same result

both using the same version of firmware

@ramadi 

Hi, Did the new Deco M4 work as the satellite Deco?

If yes, do you have any wired laptop, and please check the laptop via cable to the new deco and check the Ethernet link speed as well as the internet speed on the computer?

https://www.tp-link.com/support/faq/2899/

I have exactly the same problem too. Connecting directly to a TP-Link TL-SG108PE Gigabit Switch and the port has negotiated at 100Mbps.

@JeffreyZammit 

Hi,

Did you connect the TL-SG108PE to the 2^nd Ethernet port of main Deco, like ISP modem----main Deco M4----TL-SG108PE?

Then you find on the TL-SG108PE web UI, the port connected to M4 got a negotiated speed of 100m/s, the rest of the ports are all 1G/s？

@TP-Link 

I have my ADSL modem connected to port 1 of the Main M4 Deco and port 2 connected to my TL-SG108PE switch which in turns connects to anther TL-SG108 switch in another room. All other connected devices with gigabit ports on the TL-SG108PE switch have negotiated their interface speed correctly. 

I also tried to relocate the ports on the switch and reboot all the devices but the Deco still connects at 100Mbps.