Can't make WhatsApp calls over Wi-fi on iOS14

I have an iPhone 11. Yesterday while it was running iOS 13, all was fine, I could make WhatsApp calls over my Wi-Fi. I updated to iOS 14 in the morning. And now when I'm trying to make a call on WhatsApp, I get this message.

I can still call normally over cellular data, but not over my home Wi-Fi. The receiving end clicks on "accept call", but nothing happens.

Internet suggests me to use VPN, since my country is blocking WhatsApp. I highly doubt it, since my country is Germany. I have deleted and installed WhatsApp again - but it didn't help. It's a corporate phone, but before today everything was working fine, so I doubt it's them.

Anybody has ever had this kind of problems?

While not the same error message, a family member was having trouble with WhatsApp and it looks like a new feature of iOS14 is the culprit.

If you open up the Settings for WhatsApp and make sure that it has Local Network access that might solve your issue