As per the STUN standards, it is said that STUN works well with full cone NAT, address restricted cone NAT and port restricted cone NAT. But STUN does not work well with Symmetric NATs. Please let me know the types of NAT that PJNATH stun implementation works well with. Also does it work for symmetric NAT?

There is no way of getting symmetric NAT to work if it's no by using a
media relay. However, AFAIK pjnath supports TURN, which does exactly
that. You'll need a TURN server, you can try: http://numb.viagenie.ca/

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