01
Match the version first
Netplay compares builds. A 1.19 host and a 1.20 client fail at the handshake, so update both sides before the session rather than during it.
Main Menu > Information > VersionBoth sides need the **same RetroArch version**, the **same core** and a **ROM with the same checksum**. The host sets input latency, the client joins by nickname - through the relay if no port can be forwarded.
Requirements
- RetroArch on both PCs
- The same ROM on both sides
- TCP and UDP port 55435 reachable
Instructions
02
Match core and content
Same core, same content checksum. Two dumps of the same game from different sources usually differ, and the session desyncs within seconds with no useful error.
⚠ warningCompare the CRC shown in the playlist for both files. Different values mean different files.
03
Start hosting
Pick the core, the content and a latency of 2 to 6 frames, then start the host. The window lists the session and waits for the client.
Main Menu > Netplay > Start Host
04
Join on the same network or by address
On a LAN the host appears in the list after a refresh. Across the internet the client enters the host's address and port, or both use the relay to skip port forwarding.
Netplay > Refresh Host List
Netplay > Connect to Netplay Host
05
Tune latency instead of guessing
Start at two frames and raise until the rollback stops stuttering. Frame delay reduces input lag but needs headroom; on a weak machine it causes the desync it was meant to prevent.
tipBoth sides must keep the same latency setting. The host decides, the client inherits it.
06
Use the relay for internet play
The built-in relay needs a nickname on both sides and no open port. It adds a hop of latency and removes the router configuration entirely.
Settings > Network > Netplay RelayCommon issues
The session desyncs immediately
Different core or different ROM. Compare both and re-download from the same source.
The client cannot see the host
Firewall blocks 55435 TCP and UDP, or the two PCs sit on different subnets. Check both.
It runs but feels sluggish
Frame delay too high or a Wi-Fi hop. Lower the latency and use Ethernet on both ends.
A core refuses to start a netplay session
Some cores do not support netplay. Switch to a core with a netplay-compatible build.
Frequently asked
Can we play different games?
No. Netplay runs one content file on both machines in lockstep.
Do save states transfer?
A working save state can be shared, but only with the same core and content.
How to undo this
Stop the host or leave the session. Nothing persistent changes; clear the netplay nickname in the settings if you want it gone.
Changelog · 1 entry
- 2026-10-31First version
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