UPNP broken on 21.05?

[jimp]

I can't reproduce any problem like that here, where I could easily reproduce the error before.

If you haven't yet, after you have updated miniupnpd manually as described above, reboot the router to ensure the correct copy is the only one being used.

It's also possible there is a lot of local traffic hitting UPnP/NAT-PMP and it's just busy at the time you noticed it.