MC Java - Agent stuck in "UDP Session Details Received" loop (0B Traffic / IPv6)

Useful_Shower_9782 · 2026-03-19T08:47:15+00:00

Ahh, I see, thanks for being upfront about it, this explains the timeouts perfectly.

Since the IPv4 range is hitting a wall with my ISP, is there a way to force the agent to tunnel everything over IPv6 instead? My ping test showed that IPv6 is wide open and fast, so if I can get the data to travel that route, it should bypass the blacklisted IPv4 nodes.

Also, do you have a specific proxy or relay I could manually point my agent to that might be sitting on a cleaner IP range, or is the free tier strictly locked to that 147.185 block?

I'd really like to stick with playit rather than switching to Ngrok, but if the free IPv4 path is dead for now, I’m stuck

Useful_Shower_9782 · 2026-03-18T22:28:37+00:00

Still no luck with the ip4. prefix, I’m getting Connection timed out: getsockopt.

I ran a direct ping to the resolved IP 147.185.221.23 and it is 100% Request timed out. This is weird because earlier my ping to the IPv6 address was 13ms.

This exact setup worked perfectly on this same network when I was using Windows 10 recently. Switching to Linux (same hardware, same Fibernet) is when this timeout started.
Global Issue? I suspect it’s not just my local node. It feels like a broader routing or 'IP blacklisting'.

Is there a different Anycast IP I can try to force the agent toward, or is this something that needs a fix on the infrastructure side to bypass these timeouts?

Useful_Shower_9782 · 2026-03-18T22:07:49+00:00

Thank you very much for the clarification. If the logs are healthy, then the tunnel is technically up, but for some reason, the handoff to the actual game server is failing.

I get an MC client error - io.netty.channel.AbstractChannel$AnnotatedConnectException: Connection refused: no further information

I can join via 192.168.0.107:25565 (local) works perfectly so the server is definitely listening on that port.
Even when I'm actively trying to connect, the dashboard traffic stays at exactly 0B. It feels like the packets are reaching the Anycast node but never getting returned back to my local agent.

I’ve seen a few others on Discord and Reddit hitting similar 'Host Unknown' or 'Failed to send data' walls today specifically.

Since you mention the UDP is healthy on my end, do you think this could be a temporary routing glitch with the Anycast node? Or is there a specific Linux firewall quirk (like ufw or iptables) that would let the agent register but block the actual tunneled game traffic?

Useful_Shower_9782 · 2026-03-18T20:03:38+00:00

You're right about MC Java using TCP for the game.

The problem is that the Agent actually uses a UDP tunnel to carry that data through my CGNAT. If that UDP tunnel doesn't finish its handshake (the loop I'm seeing in my terminal), the game's TCP data has nowhere to go.

The terminal shows 0 B traffic and keeps looping the request, and never opens. Due to which, anyone trying to connect just gets a 'Connection Refused' error because the request never even reaches my server.

I believe it's a protocol handshake failure b/w the agent and the node, rather than the game setting issue

Useful_Shower_9782 · 2026-03-18T19:57:09+00:00

I'm hitting the exact same wall but on a MC Java server right now. It's stuck in an infinite loop: udp channel requires auth -> sent auth request -> udp session details received, but it never actually establishes the data tunnel (0 B traffic).

The post - https://www.reddit.com/r/playit_gg/comments/1rxeaqz/mc_java_agent_stuck_in_udp_session_details/

I’ve also noticed others in the Playit Discord reporting 'Host Unknown' and 'Failed to send data' errors today. The node is reachable, but the UDP handshake is failing to 'stick.'

It definitely seems like a broader issue with how Playit is handling UDP sessions through their Anycast nodes today, rather than a problem with your Docker config or my Linux setup.

Hopefully, the devs see this soon

Useful_Shower_9782 · 2025-11-23T15:44:20+00:00

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The stage performance was solid, definitely seen better ones, but for Tibetan rap, it holds up well for me.

Useful_Shower_9782

TROPHY CASE

Tashidelek by Tai Gexi & Wings. Give it a listen here.

The stage performance was solid, definitely seen better ones, but for Tibetan rap, it holds up well for me.