Firewalls and port forwarding

As of recently, on my Windows PC, Syncthing creates seemingly endless firewall prompts, even if I tell the firewall to allow Syncthing to do anything it likes. Might the problem have to do with lack of port-forwarding, or with ‘upnp’? I found this page of instructions, but the instructions are unclear. For one thing: the instructions leave it unclear whether I need any kind of port-forwarding at all. Do I? If I do, just how do I set it up? Thanks.

(I found two other questions along similar lines on the forum. However, I do not understand the answers to those questions.)

I think the prompts are per binary (every time syncthing upgrades you’ll get a prompt) rather than per port.

You shouldn’t need to do anything special for syncthing, unless you have a firewall that prevents outgoing connections in general.

Thanks. So: I should not get all those firewall prompts. Yet, I do. I think my VPN or VPN software might be to blame, though it is only Syncthing (and, occasionally, Thunderbird) that seem affected (i.e. other programs are not).

EDIT: I am using the Wireguard VPN software.

EDIT: My firewall is set to allow Syncthing to do what it needs to do (as per the part of instructions - on firewalls and syncthing - that I understood). And my firewall is set to prompt for connection attempts which do not match a rule. It is those prompts that I am getting - even if I create a firewall rule giving Syncthing carte blanche. I wonder whether anyone else has this problem?

By the way, I forgot to link the instructions that I mentioned (and for some reason the forum was letting me edit the post but not save the edit). The instructions at issue are here.

Sadly, I don’t know, try disabling your VPN and see if that happens.

Thanks. And silly of me not to try that - disabling the VPN. I just tried it. The problem goes away. I will write to the people who make the software.