WhatsApp Notification Delay Again after last iOS update

I have had similar problems to other iPhone users with WhatsApp notifications being delayed. This results in WhatsApp calls also not coming through immediately. The only issue I could find is that it seems to be linked to the perceived 'weak security' of wifi connections. The matter had resolved itself with the iOS 17 update. Now, with the recent iOS 17.2.1 update this week it is back to not working! WhatsApp message notifications are once again delayed on wifi connections. I don't believe that this could be a WhatsApp app developer issue. Anybody who has been able to sort out this problem, could you please assist? Thanks.