Hi there. Here’s what you can try:
1) Keep the iPad un-updated (just in case), and remove the accessories that don’t work with the new updates.
2) Using your updated iPhone, set up the devices again and see if they work. If they don’t set up using your iPhone or still don’t work, you should set it back up using the iPad.
3) If the device is able to be reset, unpair the device and reset the accessory before trying to set it up again.
4) if it still doesn’t work, I would recommend providing the iOS team information on the accessory and when it stopped working by reporting an iOS bug: Feedback - iPhone - Apple
I hope this helps to solve your issue.