in new flat, with exact same wifi repeater, but bulbs disconnect at 50%

hi there, i’ve always managed to fiddle around and get these to work when i needed to reset them say if we got a new interenet provider etc. But i’ve moved to a flat upstairs, with the same Virgin package. I use the same wifi extender to split into 2.4 and 5ghz so that i can make the bulbs work without asking everyone else in the flat to reset all of their devices to a split bands from the main router. But there’s a new update on the Yeelight app. this time it tries to automatically connect to the bulbs and so on. But it doesn’t work. I’ve tried doing it manaually as well, about 50 times now, but all the options say device disconnected at 50%. So this is now a waste of money for me to have 5-6 of yeelight bulbs and none of them work.

does anyone know a workaround the set up process? i’ve checked that AP or WAP something is enabled which I read on another message about this problem online. Am I supposed to click ‘always connect’ or ‘only this time’ on my phone wifi when the app prompts me to choose? and am i supposed to have 5G /data on when i do this? should i be connected already to the 2.4ghz on my phones wifi or does it not matter? thankyou so far i’ve tried connected my phone to the router, and also the 2.4ghz band i have on my wifi repeater. i’ve also tried connecting the yeelight bulb to both and tried all options.