So on my Asus DSL-AX82U-AX5400, under Lan I get that a device o LAN 4 can be improved, but it can not, the device is a Philips hue bridge, that is 100mb Lan type.
This has only been since latest firmware since you added the Lan port check. There is no issues just a pain its reporting incorrectly
Yeah, it's a fairly useless feature and a bit misleading in what it says about 100M devices. Fortunately it's easy to ignore, although it may have people who don't understand Ethernet all that well chasing a problem that doesn't exist.
Indicating port speed in the GUI is a good thing, classifying connections that are actually working properly as a warning and saying they could be improved is not so good.
I had a 2.5 Gbps switch connected to one of the 10 Gbps ports on my AXE16000 and it was definitely annoying to see that notice. (The 2.5 Gbps port matches the output of the cable modem). Eventually I got a 10 Gbps switch and moved the 1 G device from the other 10 G port to a 1 G LAN port for my sanity. Everything is green now except if I turn on the Xbox 360 which only supports 100 Mbps.
I guess as a “workaround” you could reinstall a 386 firmware version. (I’d just live with it).