i have 1 deco x68 unit that keeps dropping all 5ghz connections once every few days to 2.4ghz only. there are 2-3 devices that connect to that deco and have full bars at all time even during 5ghz connection. There is a roku express maybe 5-10ft away and that will drop down to 2.4ghz. The issue resolves itself soon as i restart the unit.

This only happened to the x68.  the rest of network holds 5ghz no problem.

my current set up is two ax5700 ( 1 main unit) and 1  connected via wireless backhaul on the same floor. The x68 is wired to main unit via ethernet backhaul.

I would say system worked for about 6-8months before this started happened.

The x68 is placed on a higher shelve away from any other possible interference. When 5ghz is working all devices pull around 250mbps even 1 wall over.

I have factory reset the deco x68 a few times. I even switched to another deco x68 from the 3 pack it came with and the issue persist. ethernet cable was replaced as well.

I did also try the network interference app and it changed the 5ghz channel. however that not resolved the issue.

These are refurbished units from ebay and are out of warranty from tplink 90days.

Any ideas would be great.