Identify the failing layer
Proton can support selected anti-cheat middleware, but EAC or BattlEye middleware availability is not equivalent to a particular game's developer enabling Linux or Steam Deck play. Server-side enforcement can reject a game even when its graphics and launcher work. The failure may be reported as a generic kick, connection rejection or missing service, and one successful local single-player launch says nothing about multiplayer admission. Treat the precise title, game branch, mode and update date as required facts.
Collect discriminating evidence
Consult the game's current official support status and Valve's developer guidance, then compare an official notice against recent user reports. ProtonDB or a forum post is community evidence tied to a time and game version, not a permanent compatibility verdict. Keep account authentication, firewall, packet loss, server maintenance and anti-cheat authorization as separate branches. A network timeout alone does not prove that anti-cheat rejected the session.
Compare safely and record limitations
Do not install unofficial kernel modules, bypass services, modify protected game binaries or disable security checks to force access. Those actions can violate terms, compromise the account or defeat intended safeguards. If the developer has not enabled Proton anti-cheat support, changing Proton versions, enabling a different GPU or using a VPN cannot create that permission. Check official status again after updates and retain dated evidence rather than publishing an invented working rating.
Gather evidence before changing the system
Run one command at a time in the relevant host or game environment. Read its requirements and interpretation first. The website displays commands and never runs them.
Read-only observation
date -IsRequirements: Run in the relevant host/session; compare with the actual game environment and redact private paths before sharing.
Record the local timestamp for comparing server or game-update changes.
Read-only observation
ip routeRequirements: Run in the relevant host/session; compare with the actual game environment and redact private paths before sharing.
Inspect the default network route; this cannot determine anti-cheat authorization.
A controlled test with a way back
Test a supported offline or single-player mode and the official online mode separately with unchanged game files.
Rollback: Return to the game's standard launch options; do not alter anti-cheat installation files.
What this test cannot establish: Game availability changes by developer decision, region, patch and mode; no bypass is provided.
Sources and scope
This editorial review uses primary project and distribution references. It does not establish that a fix has been reproduced on your hardware. Installed versions, the game runtime and the selected graphics API can change the result.
- Valve Steamworks Proton anti-cheat guidance
Anti-cheat support depends on individual game-developer enablement.
- Valve Proton runtime and logging
Valve documents per-game Proton logging and runtime options.