Dedicated Server Steam Group ID verification fails for confirmed group members

When a dedicated server has a valid Steam Group ID set in `<GroupID>`, confirmed members of that group are rejected with the error "You are not in group" when attempting to join. The only workarounds are adding players to `<Administrators />` (which grants full admin privileges) or setting `<GroupID>` to `0` (which removes all access control), both of which are unacceptable for a server that simply needs a basic join restriction.

Reproduction Steps:

1. Create a Steam group

2. Add at least one player to the group and confirm membership via `steamcommunity.com/groups/[GROUP]/memberslistxml/?xml=1`.

3. Configure a dedicated server with `<GroupID>[ID]</GroupID>` using the correct 64-bit ID, <groupID64>, from the XML file.

4. Attempt to join the server using the Steam account listed in the member list <steamID64>.

5. Receive "You are not in group" error despite being a confirmed member.

Expected Behavior:

A confirmed member of the specified Steam group should be able to join the server.

Actual Behavior:

The player is rejected with "You are not in group" even though the SteamID64 matches exactly what Steam's own group member XML returns.

Environment:

- Game: Space Engineers 1.210.014 b0 (PC, Steam)

- Mode: Dedicated Server, Survival, Public

- Network: Steam

- Config: `<GroupID>103582791476112699</GroupID>`, `<OnlineMode>PUBLIC</OnlineMode>`, `<NetworkType>steam</NetworkType>`

Additional Context:

This issue has been reported by the community since at least 2014 (Steam discussions, Keen forums) with no resolution. The group ID feature appears to be non-functional for its intended purpose. The only reliable access-control mechanism currently is the `<Administrators />` list, which is not a substitute for group-based joining (it grants god-mode admin rather than normal player access).

https://steamcommunity.com/app/244850/discussions/0/540743212292191596/

Group Members List XML: https://steamcommunity.com/groups/realdrank/memberslistxml/?xml=1

Excerpt from config:

  <Administrators />
  <Banned />
  <GroupID>103582791476112699</GroupID>
  <ServerName>Drank</ServerName>
  <WorldName>Star System</WorldName>
  <VerboseNetworkLogging>false</VerboseNetworkLogging>

Thank you!

Logs:

2026-10-19 23:01:30.851 - Thread:   1 ->  Game ready... 
2026-10-19 23:01:30.914 - Thread:   1 ->      Loading voxel 'Z:\appdata\space-engineers\SpaceEngineersDedicated\Content\VoxelMaps\MediumStoneIronCoreStoneCoverage.vx2'
2026-10-19 23:01:30.957 - Thread:   1 ->      Loading voxel 'Z:\appdata\space-engineers\SpaceEngineersDedicated\Content\VoxelMaps\MediumStoneIronCoreStoneCoverage.vx2'
2026-10-19 23:01:33.720 - Thread:   1 ->  ### Build Info :: CheckVSLP: CheckVSLP: Done checking VSLP events, all ok! (preAssigned=0; erased=0; total events=56)
2026-10-19 23:02:00.711 - Thread:   1 ->  GC Memory: 457.9849 / 457.9849 MB
2026-10-19 23:02:30.693 - Thread:   1 ->  STATISTICS LEGEND,time,ReceivedPerSecond,SentPerSecond,PeakReceivedPerSecond,PeakSentPerSecond,OverallReceived,OverallSent,CPULoadSmooth,ThreadLoadSmooth,GetOnlinePlayerCount,Ping,GCMemoryUsed,ProcessMemory,PCUBuilt,PCU,GridsCount,RenderCPULoadSmooth,RenderGPULoadSmooth,HardwareCPULoad,HardwareAvailableMemory,FrameTime,LowSimQuality,FrameTimeLimit,FrameTimeCPU,FrameTimeGPU,CPULoadLimit,TrackedMemory,GCMemoryAllocated,PersistedEncounters,EncounterEntities, DRS
2026-10-19 23:02:30.694 - Thread:   1 ->  STATISTICS,0,0,0,0,0,0,0,12.64168,1.077584,1,0,460.002,2661.758,3866,296134,14,0,0,0,0,0,0,16.66667,0,0,100,1768162428,460.002,0,0,-1
2026-10-19 23:02:30.695 - Thread:   1 ->  MEMORY LEGEND,Srv,Uav,Read,Debug,Index,Audio,SrvUav,Vertex,Buffers,Physics,Planets,Systems,Textures,Indirect,Constant,RwTextures,Dx11Render,MeshBuffers,FileTextures,DepthStencil,TileTextures,Voxels-Native,CustomTextures,HeightmapFaces,Mesh GPU Buffers,BitStreamBuffers,GeneratedTextures,FileArrayTextures,NativeDictionaries,CubemapDataBuffers,HeightDetailTexture,MyDeviceWriteBuffers,ShadowCascadesStatsBuffers,AI_PathFinding,EpicOnlineServices,EpicOnlineServicesWrapper
2026-10-19 23:02:30.695 - Thread:   1 ->  MEMORY VALUES,0,0,0,0,0,0,0,0,0,78,849,1686,0,0,0,0,0,0,0,0,0,0,0,384,0,0,0,0,758,456,8,0,0,0,0,0
2026-10-19 23:02:30.711 - Thread:   1 ->  GC Memory: 460.0098 / 460.0098 MB
2026-10-19 23:02:47.461 - Thread:  23 ->  Peer2Peer_SessionRequest [007...701]
2026-10-19 23:02:50.860 - Thread:   1 ->  ClientConnected [007...701]
2026-10-19 23:02:50.869 - Thread:   1 ->  OnConnectedClient Orth attempt
2026-10-19 23:02:51.978 - Thread:   1 ->  Server ValidateAuthTicketResponse (OK), Steam ID:[007...701] Owner ID:[007...701]
2026-10-19 23:02:52.164 - Thread:   1 ->  User left [007...701]
2026-10-19 23:02:52.165 - Thread:   1 ->  Disconnected: [007...701]
2026-10-19 23:03:00.717 - Thread:   1 ->  GC Memory: 462.3899 / 462.3899 MB
2026-10-19 23:03:05.261 - Thread:  23 ->  Peer2Peer_SessionRequest [007...701]
2026-10-19 23:03:08.578 - Thread:   1 ->  ClientConnected [007...701]
2026-10-19 23:03:08.579 - Thread:   1 ->  OnConnectedClient Orth attempt
2026-10-19 23:03:09.712 - Thread:   1 ->  Server ValidateAuthTicketResponse (OK), Steam ID:[007...701] Owner ID:[007...701]
2026-10-19 23:03:09.897 - Thread:   1 ->  User left [007...701]
2026-10-19 23:03:09.898 - Thread:   1 ->  Disconnected: [007...701]