@CristMog 

I own the router and if you pick it up and feel the underside it is very hot. The vents on the router are miniscule, there is not even a small fan to promote airflow on the inside, the plastic is essentially retaining the heat, and the chipset on ax routers by default are hotter than ac routers. The overheating issue affects the chipset which in turn will affect all aspects of performance, including loading the console page.

I think I figured out the issue.

I deleted the app and did a factory reset, still wasn't getting the 450 MBPS I was getting through LAN. The speeds were still at 140 MBPS, the same I had before resetting the router, I accidentally turned on the Smartconnect and the speeds were suddenly at 450 MBPS with WiFi. 
 

I restored my back up file and enabled Smart Connect, I can avoid the annoying process to reconnect all the smart devices because 2.4 GHz connection was used for their setup. 
 

My guess is the channels were causing the issue or the router caps the speed when multiple bands are used.  

@gramesmith 

That's interesting. I'm not actually using Smart Connect and I'm running 2 separate SSIDs(personal preference, I don't want devices deciding which to jump on). 

I actually just checked my bandwidth last night again since I factory reset and didn't set the tether app back up and I'm still pulling 940mpbs down over a wired connection.

I'm still inclined to believe there's an issue with the Tether app(and possibly other issues) but I'm good where I'm at now, I don't need the app.

This experience was enough to get TP-Link axed off a list of potential switch replacements for our physical security infrastructure. Petty sure, but I have concerns that every post I've seen from TP Link on their forums is disregarding that there is any issue here at all. I don't want any stress added to what I do at work 😆. Maybe their equipment is great at that level but this has really raised concerns with their ability to recognize and address issues.

Anyway I'm glad you got it resolved! All of these resolutions are absolute nonsense whatever may be going on here whether its overheating/Tether/Smart Connect etc and should have been addressed by now by TP Link!

@FearTheClown 

i reinstalled the tether app, the speeds are not affected so far. I will mess with the channels after disabling Smartconnect and update here again. 

Is there update on a fix to the router firmware? 
No QoS (trigger the slow behavior), no device prioritization (trigger the slow behavior) and no traffic monitor. 
This router is the worst purchase i have made from tplink, the AX20 feel like a complete solution in comparision. 

@JoelS This is 100% STILL an issue. I had my ISP telling me it was my router and after arguing with them for multiple hours decided to try forums. Nothing worked until I reverted to factory settings (I had tried that before and nothing) AND removed the app. Instantly lightning fast speeds again. Delete the app!

100% The. App. Is. The. Issue.

Had an Xfinity service guy out less than an hour ago. He tested everything, checked the cords, ran tests, and confirmed that my modem was pulling in what it should from their line. He so confirmed the modem was putting out at or slightly above what my plan is of 400Mbps.

The issue was the Tether app. Uninstalled the app and instantly saw speed increases. Was getting about 100mbps with app regardless of 2.4ghz or 5ghz. Deleted the app and got about 150Mbps. With app deleted, factory reset the router and now I get speeds of 400Mbps+

@MWarren90 that's insane, I just had my isp send someone this morning with the same issue. I'm gonna try deleting the app and see. Unfortunate to see this still being reinforced a year later than when this thread started. I usually never have any major issues with tp link stuff. Besides the speeds not being on par, everything with my ax3000 works flawlessly.

@slade.james please post back with your results after deleting and a factory reset. I'm still rocking fast speeds 24+ hours later