autovideosink not displaying

[Lane]

Hi,

I'm sending a gstreamer videotestsrc from one host to an autovideosink
on another host within a VPN. With the use of a VPN, the sender and
receiver are on the same subnet. The problem is, even though I can see
packets arriving from the remote host via the VPN, as shown by
wireshark, nothing is displaying on the receiving side. However, it
works just fine on localhost or on a local subnet from one machine to
another.

I send with the following:
    $ gst-launch-1.0 -v videotestsrc ! video/x-raw,framerate=20/1 !
videoscale ! videoconvert ! x264enc tune=zerolatency bitrate=500
speed-preset=superfast ! rtph264pay ! udpsink host=$HOST port=$PORT

And receive with:
    $ gst-launch-1.0 -v udpsrc port=$PORT caps = "application/x-rtp,
media=(string)video, clock-rate=(int)90000,
encoding-name=(string)H264, payload=(int)96" ! rtph264depay !
decodebin ! videoconvert ! autovideosink

Any thoughts as to why this isn't working over a VPN?