RTCPeerConnection.OnRtpClosed: dtls handshake failed

[naz-monitor]

Hi all,
First time working with SipSorcery as I need to implement WebRTC in our C# app. Basically I'm trying to connect to a customer server that will stream video to my C# app (.Net 4.7.2). I've reached a point where an offer is sent and answer received with the agreed video/audio codecs, local and remote descriptions set, ice candidates exchanged, but then for some reason the connections get closed.

Here's the last few lines of output I get. All the logs are from the hooked events on the RTCPeerConnection.

ICE CONNECTION STATE CHANGE connected
RTC PEER CONNECTION STATE: connecting
RTP DATA RECEIVED: 64103 [::ffff:xx.xxx.199.117]:49821, BYTE ARRAY LENGTH: 137
ON RTP CLOSED: dtls handshake failed
RTC PEER CONNECTION STATE: closed
RTC PEER CONNECTION STATE: failed

After some searching I only found something for Pion relating to renegotiation: sipsorcery/webrtc-echoes#14 but I'm not sure any of that applies to my situation.

Am waiting to hear from the customer side to see if they can spot anything, but other than that, I'm not sure how to progress. Any help appreciated!