Have the above router and am located in the UK.
Keep seeing this message along with the MAC address which matches one of my three active Roku devices
Have two of the streaming stick 4K and one Express 4K active on the network.
The 2.4Ghz and 5 Ghz bands share the SSID, band steering is enabled and while 5Ghz is fixed to channel 48, 2.4 is set to auto)
Any idea why I keep seeing this message?
Is the one showing the problem connected to a 4k TV and trying to stream 4k content?
Did your ISP provide the router (I know a couple of less common ISP provide devices from this brand).
If so, ask ISP support for an explanation.