Slow performance or requests timing out due to MTU value

Service Tunnel Troubleshooting

  • Updated on Oct 08, 2025
  • 2 minutes to read

Overview

Sometimes end users experience slow network performance or request time outs as a result of an MTU value that is too high for the underlying network path.

Symptoms

  • Slow network performance
  • Websites stalling or only partially loading

Potential Root Cause

The Maximum Transmission Unit (MTU) value set is too high for the network. This results in oversized packets getting fragmented or dropped, which causes latency or broken connections. Requests may only partly work or not work at all, depending on if the network can handle byte fragmentation.

Resolution Steps

  1. Navigate from Settings > Preferences in the CSE desktop app, and adjust the MTU Value for your Service Tunnel. Note that the MTU Value entered must be between 1200-1500.

Note: Lowering the MTU Value will reduce throughput and can increase network latency.