Why can't some players connect to my multiplayer game?

Because the connection is failing at some stage: NAT/firewalls blocking peer-to-peer connections (a classic 'can't connect to host' cause on home networks), the server being down, overloaded, or unreachable, matchmaking failing to place the player, or a region/routing problem. Failures hitting some players (especially in P2P) suggest NAT issues; failures hitting everyone suggest server or matchmaking problems.

Why can't anyone connect to my game at launch?

That pattern, everyone unable to connect, points at server or matchmaking infrastructure: your servers are down, overloaded by the launch surge, or unreachable, or matchmaking is failing globally. Ensure your servers are up and have capacity (load-test before launch, since launch traffic often far exceeds testing). Universal connection failure is almost always an infrastructure or capacity problem, not a per-player one.

How do I fix peer-to-peer connection problems?

Implement NAT traversal so players behind restrictive home-network NATs can establish direct connections, with a relay fallback for when direct connection fails, so those players connect through a relay instead of being unable to join. NAT/firewall blocking is a major cause of P2P 'can't connect' failures, and don't rely on players manually port-forwarding, almost none will, so traversal plus relay is the real fix.

Why Can't Some Players Connect to My Game?

Quick answer: Some players can't connect to your game because the connection is failing at some stage: NAT/firewalls blocking peer-to-peer connections (a classic 'can't connect to host' cause on home networks), the server being down or unreachable, matchmaking failing to place the player, or a region/routing problem. Failures hitting some players (especially in P2P) suggest NAT issues; failures hitting everyone suggest server or matchmaking problems.

Players unable to connect can't play at all, a complete barrier. Connection involves several stages (reaching a server, matchmaking, establishing peer connections), and a failure at any stage blocks the player. Finding which stage fails for the affected players is the diagnosis.

Why Players Can't Connect

Connecting involves stages that can each fail. NAT/firewall issues: for peer-to-peer connections, NATs and firewalls block the direct connection between players (home networks don't allow unsolicited inbound connections without NAT traversal), a classic cause affecting some players/pairings. Server down/unreachable: if connecting requires reaching your server (matchmaking, authoritative server) and it's down, overloaded, or unreachable, no one can connect. Matchmaking failures: the system fails to place the player. And region/routing: players in certain regions can't reach the server.

So 'can't connect' has multiple possible failure stages. Failures hitting some players (especially in P2P) strongly suggest NAT/firewall problems; failures hitting everyone suggest server or matchmaking issues; regional failures suggest routing/regional servers.

How to Diagnose and Fix It

Capture where and why connections fail, a connection-failure stage/error (couldn't reach server, NAT traversal failed, no match, region error) is the key diagnostic. Is it everyone (server/matchmaking), specific players (NAT/firewall), or specific regions (routing)? Bugnet captures errors with context, so connection failures and patterns surface, and server crashes/outages show in crash data.

Fix the failing stage: for NAT in P2P, implement NAT traversal with a relay fallback (so players behind home NATs connect); for server availability, ensure servers are up and have capacity (load-test for launch); for matchmaking, fix the failures; for regions, provide regional servers. See our guide on fixing players unable to connect.

Can't-connect fails at a stage: NAT blocking (P2P), server down, matchmaking, or region. Capture which, then add NAT traversal/relay, ensure server capacity, or fix matchmaking.