DP stop working

[kd01gh]

Hello!
I have 3 servers with DP (latest version, as server and client). Today all of them stopped working.
Server side error:

HTTPSRV : 2026/06/23 10:07:38 server.go:3648: http: TLS handshake error from 15.156.110.125:56092: tls: no cipher suite supported by both client and server; client offered: [c02f c030 c013 c014 9c 9d 2f>
HTTPSRV : 2026/06/23 10:07:38 server.go:3648: http: TLS handshake error from 15.156.110.125:42245: tls: client offered only unsupported versions: [302]
HTTPSRV : 2026/06/23 10:07:38 server.go:3648: http: TLS handshake error from 15.156.110.125:2992: tls: client offered only unsupported versions: []
HTTPSRV : 2026/06/23 10:07:38 server.go:3648: http: TLS handshake error from 15.156.110.125:42230: tls: client offered only unsupported versions: [301]
HTTPSRV : 2026/06/23 10:35:00 server.go:3648: http: TLS handshake error from 66.228.37.167:61000: tls: missing signature_algorithms from TLS 1.2 peer

Any idea how to fix it?

Thank you in advance.

Server config:

auth basicfile://?path=/opt/dumbproxy/passwd&hidden_domain=asdasdffgvfdsv.com?else=reject-static://?code=403
bind-address :443
cert /opt/dumbproxy/fullchain.pem
key /opt/dumbproxy/key.pem

Client:

proxy h2://USER:PASSWORD@IP:443?sni=ozon.ru&utls-fp=HelloFirefox_Auto

iOS app (TrustTunnel) stopped as well.

[Snawoot]

Hello,

Try to lower TLS version negotiated by the client:

proxy h2://USER:PASSWORD@IP:443?sni=ozon.ru&utls-fp=HelloFirefox_Auto&max-tls-version=1.2

If that doesn't help, basically, only following can be done:

• Tinker with other TLS settings (SNI, ...), port number and so on.
• Check if any TLS actually can work on that server or it has basically TLS blacklisted. If that's the case, probably switching hosting provider may help.

[Snawoot]

@kd01gh Looks good. Please also try openssl s_client -connect IP:443 -crlf and type manually some HTTP request:

GET / HTTP/1.1
Host: test

(note empty line after non-empty lines). If there's some response, I think handshake actually gets established, but connection gets choked afterwards. If that's the case, please add fetchrandom=100000-500000 to dumbproxy upstream proxy options and see what's on the client side. Maybe some new SNI is needed as well, such as ads.x5.ru.

If it happens only OpenSSL can punch through, see also that part in wiki: https://github.com/SenseUnit/dumbproxy/wiki/How-to-control-dumbproxy-client-and-server-TLS-fingerprints#delegation-of-tls-operation-to-an-external-program

[kd01gh]

GET / HTTP/1.1
Host: test

HTTP/1.1 400 Bad Request
Content-Type: text/plain; charset=utf-8
X-Content-Type-Options: nosniff
Date: Wed, 24 Jun 2026 10:29:25 GMT
Content-Length: 13

[kd01gh]

No luck.
Client side:
ERROR Can't satisfy CONNECT request: garbage body fetch failed: http2: client connection lost

Will try with docs in link.

[kd01gh]

It was SNI problem. Found good one.

[kd01gh]

@Snawoot Thank you very much for your help!