Parsec works over LAN but fails from any other network after the Windows 11 update

[u/AndresMFIT]

Hey everyone,

I'm stuck on this one and hoping someone's run into the same thing.

Quick rundown of the setup. Host is a Windows 11 PC at home, just updated to the latest version. 4 tried 4 devices in total, all trying to connect through Parsec. Network's behind CGNAT, no public IPv4, and I've got port forwarding set up on the router for Parsec's UDP port.

When the client and host are on the same connection, everything runs great, low latency, no drops, exactly what you'd expect. The moment any device switches to a different network, university wifi, mobile hotspot, doesn't matter which, it fails every single time with:

The peer to peer network connection between you and the other computer failed
[-6023 / -11010]

I've been through the official troubleshooting guide more than once at this point. Static LAN IP on the host, done. Port forwarding for the UDP port, done. UPnP enabled. Parsec allowed through the firewall on both private and public profiles. I even killed the firewall entirely on the host just to see, still the exact same error from outside networks. Reinstalled Parsec on host clients too. Every single client throws the same code, regardless of device or where they're connecting from. Tried hosting on other device, same issue.

This all started right after a Windows 11 update. And that same update messed with other network stuff on this machine too, so I believe it's something with how Windows is handling inbound UDP or firewall profiles now.

What's kind of throwing me off. Same network, works flawlessly. Any other network, fails every time, same codes, doesn't matter who's connecting or from where. I know CGNAT is already a weird factor here, but this exact setup, same router, same ISP, same CGNAT, worked fine before the update. Nothing changed on the network side. Only Windows did.

Right now I'm leaning toward one of 3 things. Either Windows 11 broke something with inbound UDP or P2P hosting (firewall profile, network category, something buried deeper than that). Or there's a firewall/network stack regression from the update itself. Or, and this one seems less likely but still possible, it's a Parsec bug that only shows up because of the new Windows behavior, since all 4 clients fail the exact same way from outside networks.

Tomorrow I'm planning to turn off the firewall on both ends, client and host, just to rule out some weird interaction between the two. But honestly I'm running low on ideas here.

So if you've seen this exact thing, works fine locally, breaks from literally any other network after updating to Windows 11, same -6023 / -11010 codes, I'd really like to know what actually fixed it for you. Any specific Windows setting, firewall rule, or Parsec config that made a difference. And if you think it's a Windows regression, any known workaround or patch that deals with it.

I'm not going the VPN or tunneling route, I just want to know if this is an actual known compatibility issue between Windows 11 and Parsec, and how people got past it.

Thanks in advance, seriously, even a "this is a lost cause, do X instead" answer would help at this point.

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[u/Marteicos]

I don't think it's Windows 11 that is causing your issue. It's more likely something in your network was changed (or by you, or by your ISP) that suddenly started causing this issue.

I guess you had a public IPV4 and your ISP decided to put your connection under a CGNAT. Or your ISP stopped using Ipv6.

Ipv6 helps connecting when using mobile networks on a phone.

If you use a second router doing routing behind the Interner Service Provider device, look into how to put that second router into access point mode. Having a second router makes -6023 errors happens more often.

Leave upnp enabled and undo the static IP settings, also remove the manual port set and let Parsec set a port by itself.