anyone?

as i said, i have 2 wired devices to test with, the fingbox and my pc.  both exhibit the exact same speeds of about 90mbps.  a reboot of the DECO fixes this.  since the connectivity of both of these devices is to the switch, which has been rebooted also in troubleshooting, the negotiation speeds will be to that, and not the deco.   and since rebooting the deco sorts the issue out, albeit temporarily, logic dictates that it wouldn't be anything to do with negotiation speeds or the connectivity to the deco itself. 

the only thing to maybe check would be the negotiation speed of the deco to the switch.  but I also doubt that is the issue too since unplugging/rebooting switch makes no difference.

the link you sent is about wireless signal strength/speeds which is not relavent to this issue since it is purely an issue with ethernet. 

as for topology, it is exactly as you would expect.   I have a modem plugging into the deco,   a few wired devices (AV receiver/tv/xbox/pc/fingbox) and a whole bunch of wireless devices connected to any of the 3 decos in the house (although since deco doesn't seem to be able to tell you which is connected to which, which is very annoying as most other mesh systems can!)

It's nothing to do with link speeds and where things are connected to,  if you read what i wrote, all of the things I have done have completely proven that to be the case. 

Right, on wednesday I took it upon myself to change the QOS setting to standard (although it already was) and removed all of the high prioirty devices (which the wired devices I am talking about were on there anyway) and set the bandwidth to manually 400/50 as opposed to the 360/30 that was in there from before.   

So far it hasnt gone down to those 90/30 speeds again.   It's only been 2 days nearly so i'm not counting my chickens yet. 

Will keep you up to date. 

As for the firmware update..."next firmware will include this" is all i ever seem to see as a reply from TPLink.  despite the fact that you only seem to release firmware updates rarely.   I was told you were going to sort the Hairpin NAT issue in the next firmware and also the fact you can ping the router from the internet in the next firmware.   these were brought up (by me) over 6 months ago.  Still nothing on either.   So forgive me if I don't take you at your word that this will be a feature in the 'next firmware' 

FYI I'm paying for 350mbps broadband

They took months to fix a problem which can actually fix in the morning before lunch time, each firmware takes few months to release and just to fix some very minor problems, and soon it become 18 months, and u will see a Deco M5 v3 been introduce, which having EXACTLY same hardware but some problems which should be solve in current version been fixed, and some simple features like Wi-Fi channels selection been finally add, BUT NOT COMPATIBLE WITH CURRENT VERSION HARDWARE. TP-Link has done this trick for so long, perhaps they still doing it now, unless someday being sued by FTC to force them release fixes firmware like what D-Link is facing now, so next time take this into account when u r making decision on what to purchase. 

Btw, stop wasting ur time listening to this OFFICIAL REPLY, they r just been hired here to calm u down and taking u running circles, not helping or listening at all, they don’t even read what we wrote properly,  disgraceful.

wow , really? thats crazy, but not altogether surprising.   I certainly won't be buying TPLink  again nor recommending it to my friends/family/work. 

very disapointing.  I doubt we'll have any kind of official TPLink comment in here from this point. 

Ok I understand where you are coming from, but I've already told you I have rebooted the switch and the router which would both disconnect and force the links to be reestablished.   only when the deco itself was rebooted does the speeds go back to normal.

Either way, since I have played around with the qos settings the internet connection has remained stable at the max speeds for the last week , so it 'seems' that the issue is related to qos.