Trying to troubleshoot low internet speed. We are paying for 200mb download speed. Our setup is as follows:

Users computer(1GB) -> Phone(100mb switch port) -> Access switch(100mb) -> Core Switch(1GB) -> Firewall(1GB) -> WAN switch(100mb) -> WAN modem(1GB switch port)

Users are only able to get max ~40mb internet speeds. I know we will never get close to 200mb since there are so many devices that are capped at 100mb but is ~40mb realistic? I checked the duplexes and they are all correct and have no issues. I checked the firewall for any bandwidth throttling and there are no rules for this. Can you guys think of what could be causing such low internet speed? Also want to note if I connect a laptop(1GB) to the WAN modem, it gets ~190mb speed, which would imply there is nothing wrong with the modem. Thanks in advance.


Here is a diagram of the network:

enter image description here

  • 2
    What network device models, and what are their configurations? We can't diagnose this without more detail. All we can do is speculate, but that is off-topic here.
    – Ron Maupin
    Sep 13, 2016 at 17:37
  • A diagram would be helpful too.
    – Ron Trunk
    Sep 13, 2016 at 17:41
  • 3
    What is the firewall model (Stonesoft has several)? What are the network device configurations? Your WAN switch only has 100 Mb ports, so you will never get over 100 Mb, and the 200 Mb you are paying for is overkill.
    – Ron Maupin
    Sep 13, 2016 at 18:21
  • 2
    Please also try to use correct units, MBps or MB/s means MegaBytes per second, and Mbps or Mb/s means Megabit per second. 8 Megabits per second (roughly) equals 1 MegaByte per second. In this case, 40 MBps would be really good (actually more than either your WAN switch could carry per port), and 40 Mbps would be bad.
    – Stuggi
    Sep 19, 2016 at 18:54
  • 4
    What you can try, after hours and after you've upgraded the WAN-switch, is to connect a laptop directly to the WAN switch and run the speed test from there. If you get what you're paying for there, you move your laptop on to directly plugged into the firewall. Then you move to the core etc. etc. preferably disconnecting all other clients while you run the test. That way you'll quickly find the non-obvious bottleneck.
    – Stuggi
    Sep 19, 2016 at 18:57

2 Answers 2


As mentioned before, your bottleneck is the WAN switch. You'll need to upgrade that device to a higher speed port, or alternatively depending on your security requirements, you could patch your modem into your core switch on an isolated VLAN. Then plug the WAN port from your firewall into another port on the core switch on the same isolated VLAN.


The first issue you have is the WAN switch. You will need to upgrade to 1gbps switch in order to fully utilize the connection from your ISP.

I would also switch the design around and have it go modem -> firewall -> switch. That way things will be managed on the endpoints in not in the middle.

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