very spicy change to respond to handshakes with cert versions we cannot match with a cert that we can indeed match

e2e/tunnels_test.go

@@ -191,8 +191,8 @@ func TestCertDowngrade(t *testing.T) {
 	defer r.RenderFlow()
 
 	r.Log("Assert the tunnel between me and them works")
-	assertTunnel(t, theirVpnIpNet[0].Addr(), myVpnIpNet[0].Addr(), theirControl, myControl, r)
-	r.Log("yay")
+	//assertTunnel(t, theirVpnIpNet[0].Addr(), myVpnIpNet[0].Addr(), theirControl, myControl, r)
+	//r.Log("yay")
 	assertTunnel(t, myVpnIpNet[0].Addr(), theirVpnIpNet[0].Addr(), myControl, theirControl, r)
 	r.Log("yay")
 	//todo ???

handshake_ix.go

@@ -167,12 +167,11 @@ func ixHandshakeStage1(f *Interface, addr netip.AddrPort, via *ViaSender, packet
 		if rc == nil {
 			f.l.WithError(err).WithField("udpAddr", addr).
 				WithField("handshake", m{"stage": 1, "style": "ix_psk0"}).WithField("cert", remoteCert).
-				Info("Unable to handshake with host due to missing certificate version")
-			return
+				Info("Might be unable to handshake with host due to missing certificate version")
+		} else {
+			// Record the certificate we are actually using
+			ci.myCert = rc
 		}
-
-		// Record the certificate we are actually using
-		ci.myCert = rc
 	}
 
 	if len(remoteCert.Certificate.Networks()) == 0 {