Do you want to sell your stuff in the EU? - Wake up and start fixing your firmware.
Literally, i have a RE450. The speed is all over the place, starts with 150 Mbit in high speed mode (ISP 300/15), degrades over time down to 50 Mbit then 20 Mbit.
The extender is somehow "nuking" the router. The connected frequency (2.4G / 5G) becomes useless after two weeks and requires router to be restarted. No, this is not "brand xyz issue, they need to fix it". I have tried 3 routers, bougth a brand new 1 Ghz dual core 128 MB ram router. It is more than enough in performance, yet your sweet little extender is able to make it choke and 5G wifi stops working.
Yes, I am on latest firmware, Yes my router is on latest firmware. I have been debugging and trying to fix this myself since i have bought the device.
I can help with debugging or whatver, just please start fixing your bugs. I do not care about your "tested in our lab environment - it is working" excuse, do you even use your orwn products at your own home? We consumers do not have your "fancy little lab environment" in our houses, so the real world use is different from what you guys are "testing".
If you do not care, at least make it open source so good people at OpenWRT or tomato forks can make use of it.
EDIT: And it took just 4 hours to degrade down to 60 Mbit. Nice...