Quick answer: Unreal OSS EOS session search returning empty on LAN despite hosts being online? EOS routes through cloud relay by default - set bIsLANMatch and configure platform LAN settings.

Two PCs on the same router. One hosts an EOS session; the other searches and finds nothing. WAN sessions resolve fine.

Set LAN match flag

SessionSettings.bIsLANMatch = true;
SessionSearch->bIsLanQuery = true;

Both sides must agree. With bIsLANMatch the OSS uses broadcast discovery instead of EOS lobby search.

Configure firewall

EOS LAN uses UDP 7777 by default. Windows firewall blocks it on private networks unless your launcher signs as Public+Private. Run netsh advfirewall to verify.

Fall back to Null subsystem

For pure LAN, the Null OSS is simpler and bypasses EOS entirely. Use OnlineSubsystem.Native for LAN-only builds.

“LAN multiplayer in an OSS-on-cloud world is the special case, not the default.”

Provide a UI toggle: 'LAN game' vs 'Online game'. The branch in code is small; the UX clarity is large.