Slow wifi with Sonicwall Global VPN
Creation date: 4/23/2019 9:48 PM
Updated: 7/7/2020 2:51 PM
If you have GVC running connected or not and notice slow speed tests (.1mbps down) but fast uploads and no drop connections please do the following.
Solution / Workaround is to disable Receive Segment Coalescing (RSC) on the wifi adapter.
Automated fix from Microsoft available here, https://aka.ms/diag_cssemerg11005
Manual disabling RSC
Automated fix from Microsoft available here, https://aka.ms/diag_cssemerg11005
Manual disabling RSC
-
Open an Administrative powershell. Start menu and search for powershell and right click and run as administrator.
- get-netadapter (This gets the network adapter names)
- get-netadapterrsc (Get the network adapter's RSC settings for each adapter)
- disable-netadapterrsc -name ADAPTER-"NAME" ( Disable-NetAdapterRsc -name "Wi-Fi" ) (This disables RSC for the named adapter, get name from step 3, usually Wi-Fi)
- get-netadapterrsc (Verifies RSC status)
To determine RSC problem.
- Please install speedtest.net app (no login required, just skip) . Speedtests in browser when you have slow downloads sometimes crashes the browser.
- Run the speedtest. If you get a good speeds 100-400mbps, then continue to Step 4.
- If you have slow speeds, turn wifi off and back on to ensure you have the closest accesspoint. Please repeat step 2 to confirm good internet. If its bad, you might have gvc 4.10 installed and downgrade.
- Run GVC. It doesn’t have to connect to vpn site to break wifi downloads with RSC.
- Do a speedtest. If you notice considerably slower downloads but normal uploads then you have a RSC problem.