I bought the RE550 to replace and older RE200. The RE200 would not connect to the 5ghz upper channels such as 157. It was working fine at 44. Called tech support. After a couple of emails it was determined that the unit would not connect to the upper channels. Also, while troubleshooting I tried to update the firmware. Do to some flaw it would not update.

I bought the RE550 and it recognized both the lower and upper channels at 5ghz from my unifi AP. My use case is special in that it is extending the AP range for a Ring doorbell 2020 release model. Being outside and at the far end of the house from the AP location adding the extender worked great for both models. The RE550 improved the signal over the older RE200. The RE500 also updated the firmware without a problem.

The use case does not normally connect to Apple mobile products but there's a tether app that can be installed either on a phone or ipad. It was then I noticed that the ipad would not resolve an IP address via pfSense router DHCP. But a laptop, Ring doorbell, and Echo Show would without issue.

Tech support once again helped with a suggestion of using the RE550 local DHCP server and it connected without issue. Not sure why Apple had a problem with the RE550 and not the RE200.

Tech support from TP-Link is great either by phone and/or email. I would recommend this product for the quality, ease of setup, price, and support

Gerald