Yee.light.color.2 keep going offline

I have been using the colour 2 bulbs for some time now and they have been great. I have 3 of them.
I recently added 3 more but color S1 this time. Since adding the S1 bulbs the colour2 bulbs have become unstable with connectivity. I have to switch them off at the wall and back on for them to connect briefly. They don’t always reconnect to my WiFi.
The new ones are fine…
All globes have been mac and IP assigned at my router.
Both colour2 and color S1 are on latest firmware.
I have also reset and set them up again and did not help.
Using the yeelight app and Google home app, can’t use ittt due to this issue.
This is seriously frustrating, please help.

Oceania server
MI ID : 6175026206