Detect STUN Server

Summary
A VPN server is listening on the remote port. Description : The remote host is running a STUN (Simple Traversal of User Datagram Protocol - RFC 3489) server. Simple Traversal of User Datagram Protocol (UDP) Through Network Address Translators (NATs) (STUN) is a lightweight protocol that allows applications to discover the presence and types of NATs and firewalls between them and the public Internet. It also provides the ability for applications to determine the public Internet Protocol (IP) addresses allocated to them by the NAT. STUN works with many existing NATs, and does not require any special behavior from them. As a result, it allows a wide variety of applications to work through existing NAT infrastructure. Make sure the use of this software is done in accordance with your corporate security policy.
Solution
If this service is not needed, disable it or filter incoming traffic to this port.