Unable to forward webtransport request via loadbalancer to origin

I am trying to get a webtransport server working. I am running this script on my server: samples/webtransport_server.py at gh-pages · GoogleChrome/samples · GitHub. Then I created a loadbalancer, and enabled HTTP/3 traffic in network tab. However when I try to connect to the server script using the test client provided by Chrome, the server script doesnt get any data, and the handshake fails. However if I directly call the server from the client (not use the loadbalancer URL), it works as expected. The server client is listening on port 2053.

Any help would be greatly appreciated. Thanks!


Is this by IP address? Or through a :orange: Proxied hostname?

Speaking of :orange: Proxied, is your load balancer here proxied? I believe it’s not necessary, and Load Balancing is handled through DNS and proxy status is irrelevant.

Hey, thanks for reply.


Its directly by IP address.

It is proxied. Do you think thats what causing the issue?

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If you’re proxying HTTP/3 (Layer 7( via the Cloudflare edge, then WebTransport won’t currently work because it is not a supported feature. WebTransport requires a SETTINGS_ENABLE_WEBTRANSPORT setting to be advertised by client and server (WebTransport over HTTP/3), which is not advertised by Cloudflare.

At the moment, you could use something like Spectrum in front of your origin for Layer 4 proxying, which would allow clients to work directly.

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