@David-TP hi, thank you for your reply. The mobile clients do connect via 5ghz but it's just the deco unit itself keeps reverting to just using 2.4ghz to connect to the main unit. It's the office one...

I have had the Deco X60 mesh for around a year and never had too many issues but now they are connecting to each other via 2.4ghz about 90% of the time. This drastically reduces our download speeds...