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How to troubleshoot a slow Internet connection

Estimated Reading Time: 1 Minutes

 NOTE: These instructions are based on using a SonicWALL firewall.  Steps may vary for other firewalls.


  1. Check the bandwidth usage graphs to verify connection is being maxed out.  Must contact the ISP for the graphs.

  2. Login to the firewall at the site having a problem
    a. Go to  System / Diagnostics
    1. Select "connections monitor" for the diagnostic tool
      b. Sort by Tx Bytes or Rx Bytes based on what is being maxed out
      c. Look at the first row and record the source and destination IP address.  This will be the connection with the most amount of bytes transmitted or received (depending on what is being maxed out; upload or download)
      d. Note: if you look at the destination port, it will give you a clue as to the type of traffic

  3. Find the computer on the inside of the network with the source IP

  4. TeamView into this computer

  5. Open a command prompt with elevated privileges (administrator)
    a. Run "netstat -anb"
    b. Find the destination IP address in the list and see what process is controlling this connection
    c. Option: open task manager to see what user is running the process and maybe kill the process


How to troubleshoot a slow Internet connection