Problem#

In OpenWrt’s cloudflared, when you use a new version (starting March or April 2024), you may see the CurvePreferences includes unsupported curve error. This is because the new cloudflared uses a new encryption algorithm, which requires an updated Go build toolchain. But the cloudflared on OpenWrt hasn’t updated its toolchain, hence the error.

Solution#

Currently, you can solve it by using an old version of cloudflared (not recommended), or by changing the parameters so it only uses the HTTP2 protocol instead of the default QUIC protocol.

Modify the run parameters and add --protocol http2. Without it, the default is auto, but that auto only uses the QUIC protocol to connect and can’t automatically switch to HTTP2 — it just reports CurvePreferences includes unsupported curve, and then shows Argo ERROR when accessing.

Referenced issues https://github.com/openwrt/packages/issues/23852 https://github.com/cloudflare/cloudflared/issues/1158