This article describes how to troubleshoot internet speed/bandwidth performance issues and requests. It also lists existing customer defects and related solution articles.
Using iPerf3 for Troubleshooting
iPerf3 is used as a primary tool to troubleshoot internet speed issues. An alternative way to measure the connection speed is to download the SpeedTest app, select the nearest server, and run the SpeedTest check.
Note: various browsers may behave differently and show different results. More accurate results can be achieved using the iPerf3 tool. For more information, please review the article Troubleshooting Connection Speed Issues via iPerf3.
Additional Troubleshooting Procedures
Resetting Kerio Control Configuration
Some customers confirmed that their upload/download speed improved after resetting the Kerio Control configuration to the default settings (Factory Reset). The configuration can be recovered/re-imported after resetting Kerio Control to the default settings.
Capturing Traffic on Server Side of Kerio Control via TCPdump
You can use TCPdump to capture traffic on the server-side when troubleshooting internet connection issues. For more information, please refer to the article Capturing Traffic on Server-Side of Kerio Control via TCPdump.
Performing Tests Without Kerio Control
To receive precise results about the actual upload/download speed provided by the ISP (Internet Service Provider), it is recommended to bypass Kerio Control and run the tests. In the VMware installation, bypassing can be done by changing Network Adapter settings from Custom (VMNet1 Host-only) to NAT.
Logs and Customer Defects
According to the tests performed by Engineering in the Lab environment, the worst performance is observed on Kerio Control Hyper-V installations. It is caused by the incompatibility of the Hyper-V and Linux drivers. The Engineering lab test results can be found in the Hyperscan iPerf spreadsheet. For more information, you can refer to the following Jira ticket: Slow download and upload performance Hyper-V.
Also, please be aware of the slow download performance in the hardware box issue, which was reported by multiple customers.
All Debug logs should be disabled while measuring the speed performance.
Please read the following articles related to the connection speed issues:
- Considering the Effect of Concurrent Maximum Users for Maximum Performance on Kerio Control
- Speed Testing Kerio Control
- Monitoring traffic in Kerio Control