@Petrinho Further to my previous message, I figured out the issue (for me at least). The power cable on the back of the Logitech Harmony hub was a bit duff so if you lifted it up slightly at the back...

@Petrinho I'm having the same issue. Just moved house and my Logitech Harmony hub was working fine on Unifi WiFi, new place installed TP-Link Deco M9 and Harmony hub only connects to WiFi for 20...