@Wayne-TP 

Was just about to try the hotspot but suddenly it's working again. 

I'd had it turned off at the wall switch for a couple of days and just turned it on and connected first time without going through the setup. Must have kept the settings for the SSID from previous attempts.

Odd as I tried it many times in multiple locations where other bulbs would connect fine. Always just that one bulb.

May be coincidence but I had updated the firmware on my access point, though for a different reason.

Or could be a stuck IP in the router DHCP and leaving it off has cleared it. Don't know really. Just have to see if it manages to stay online.

Out of curiosity though, do the Tapo bulbs require and Internet connection, ie can't work locally if the Internet is down / depends on cloud service? 

Just wondering if the Tapo don't have the annoying noise issue the Kasa do. Then I could have one in the bedroom and leave it on at the mains. I have to turn the kasa off at the switch at night because it annoys me and I hear the bulb noises in my sleep! 

  @Wayne-TP 

Thanks. Would the same be true when used with Home Assistant? 

I went with Kasa originally and there were concerns with Tapo compatibility with Home Assistant some years back and HA in particular is designed to not rely on an Internet connection and third party cloud services for privacy as well as Internet connectivity. HA would provide the automation, as it does with my Kasa bulbs.