Networking

Steam's networking carries game data between players without either of them needing a public IP. Traffic can route through Steam's relay network, which hides player IP addresses and gets through NAT that direct connections cannot.

This sits alongside Unreal's replication rather than replacing it.

Hosting and connecting

Prefer the P2P nodes for player hosted games. The IP nodes listen on a real socket, so player addresses are visible to each other and NAT traversal becomes your problem instead of Steam's.

A typical host flow

A client just calls Connect To Peer with the host's Steam ID and waits for On Connected.

Relay readiness

Relay access is requested automatically at startup and takes a few seconds to become ready. Get Relay Status reports progress. Connections started before it is Current simply take longer rather than failing.

Ping without connecting

Get Local Ping Location returns an opaque token describing where this machine sits in Steam's relay network. It is not geography and not an IP address, which is what makes it safe to publish.

Put it in your lobby data and any other player can estimate their ping to you without either of you connecting first:

That is how a lobby browser sorts by latency honestly. Check Is Ping Data Ready first, since Steam needs a few seconds after startup to measure.

Connection lanes

One connection normally means one queue, so a large reliable message blocks everything behind it until it finishes.

Configure Connection Lanes splits a connection into independent priority queues, so a 4 MB asset transfer stops delaying the position updates travelling beside it. Send Bytes On Lane chooses the queue.

Lower priority numbers send first. Lanes sharing a priority split bandwidth by weight.

Configure lanes right after the connection opens and before sending anything. Steam will not shrink the lane count afterwards.