How to Fix Lag
Try these first — they're free and solve the problem for most people.
01 Sort the server browser by ping and join the lowest-ping server
1. In ACC, go to Multiplayer > Server List 2. Click the Ping column header to sort servers by latency 3. Choose a server under 50ms if possible 4. Avoid servers with 150ms+ unless there is no alternative at your skill rating 5. If all servers in your region show high ping, the problem is your ISP routing, not the game
Immediately improves the experience if you were previously connecting to distant servers. No cost, no tools needed.
02 Switch to Ethernet and disable WiFi
1. Connect your PC to your router using an Ethernet cable (Cat5e or Cat6) 2. Open Windows Settings > Network & Internet > Wi-Fi 3. Toggle WiFi off to prevent Windows from falling back to wireless 4. Restart ACC and check the connection indicator 5. If ping drops and becomes more stable, WiFi was the source of jitter
Eliminates wireless jitter. The most impactful single change for WiFi users. Sim racing is uniquely sensitive to jitter because braking consistency requires stable, predictable latency.
03 Pause downloads and close streaming apps before racing
1. Pause Windows Update (Settings > Windows Update > Pause updates for 1 week) 2. Close torrent clients, Steam downloads, Epic Games downloads 3. Close browser tabs playing video (YouTube, Twitch) 4. Disable cloud sync (OneDrive, Google Drive, Dropbox) in system tray 5. These consume upload bandwidth — in ACC, upload congestion makes your car 'freeze' on other drivers' screens, causing them to collide with you
Prevents upload congestion that triggers phantom contact from other players. Particularly important at race start with 24 cars.
General network tips (not Assetto Corsa Competizione-specific)
04 Check ping and packet loss in the ACC session HUD
1. Launch ACC and join any server (practice or race) 2. During the session, look at the network status icon in the top-right corner of the screen 3. Green = good connection (<50ms, <1% loss) 4. Yellow = degraded (50-100ms or intermittent loss) 5. Red = poor (>100ms or significant packet loss causing teleporting) 6. If you see yellow or red and your ISP is otherwise fast, the issue is routing, not bandwidth.
Diagnostic only. Identifies whether your connection issue is actually network-related before trying fixes.
05 Flush DNS and reset the Windows network stack
1. Open Command Prompt as Administrator 2. Run: ipconfig /flushdns 3. Run: netsh winsock reset 4. Run: netsh int ip reset 5. Restart your PC 6. This clears stale routing tables and DNS cache that can cause sudden ping increases
Fixes routing anomalies caused by stale network state. Quick fix when ping suddenly worsened for no apparent reason.
06 Enable QoS on your router for gaming traffic
Access your router admin panel. Enable QoS and prioritise UDP traffic on port 9600, or prioritise acc.exe by application name. This ensures ACC packets are sent immediately even when other devices are downloading.
Most impactful in households with multiple users. Prevents ACC packets from queuing behind streaming or download traffic.
07 Forward ports if hosting or consistently experiencing connection drops
In your router, forward UDP 9600 and TCP 9601 to your PC's local IP. While ACC clients do not need open ports to join servers, some ISP NAT configurations cause intermittent connection drops that port forwarding resolves.
Fixes intermittent disconnections on strict NAT connections. Not needed for most players on moderate NAT.
Still lagging? The problem is likely your ISP's routing to the game servers.
PingAim detects Assetto Corsa Competizione automatically
No manual config. PingAim identifies Assetto Corsa Competizione by process name and routes it through your fastest connection using a kernel-level WFP driver.