Slow Internet Connectivity on my Network

  • 10 May 2016
  • 6 replies

I have very poor internet connectivity at the workplace, We have about 500 Users on the network,. Users complain of their inability to access common webpages such as : Yahoo, Gmail and the rest. But strangely Youtube is able to open faster and even play video seamlessly. I have observed and confirmed their problem. Making me doubt if its a bandwidth issue from the ISP I have an Enterasys XSR-3150 router that sits between the ISP and my network. I connected my laptop directly to the ISP ODF Core using static IPs and it resolves webpages very fast. Some advice as to diagnosing the problem will be very much appreciated.

6 replies

The first steps are to review the revision of firmware installed (CLI "show version" and review the running configuration of the router (CLI "show run"). Look to see if there is any QoS configured and if so how is it applied to the interface(s).

Check to see how the clients are getting their IP address, gateway, and DNS information. Look also for any Policy Based routing,, verify the route tables are correct, and examine any firewall configuration or blacklist/whitelist entries.

I recommend that you call Extreme Networks GTAC and log a service case for troubleshooting.

Raymond Jerome
I have had some similar circumstances in the past, only for me it was the other way around. That is, YouTube would tank for me while all else was lightning. Still, I would look into and resolution as a possible cause. What do you have your clients set to use for DNS? Is it an internal DNS server? If so, is that server set up to forward to an external DNS that your ISP has provided you? When you are testing outside of your firewall, what are you using there for DNS? Many times I have seen things set up to where the clients primary DNS server is set to an internal server and their secondary is set to an external server, and it just "don't work that way". They should all point to one or two internal servers only. And then those servers should have your ISP's DNS set up as forwarders. Also if you have no forwarders configured, you are asking your internal servers to query the root internet servers for common DNS queries. They will eventually get you an answer ... but it's very slow.
Userlevel 3
Hi eberrick,

If you have not done so already, if you know some IP addresses of external destinations you can try bypassing the DNS servers by entering those IP addresses in the URL field. If the response is normal, then this would point to a possible DNS related issue as Steve and Jerome mentioned previously.
Userlevel 3
To add to the responses already provided, you can also attempt to point an internal client/host to a Public DNS server (such as one of Google's Public DNS servers --> e.g. IP address = and see if the response time improves. If you no longer observe slow responses when pointing to a public DNS server, this would indicate a possible issue with the originally configured DNS server(s).
Userlevel 7
Hi eberrick, were you able to solve your connectivity problems with any of the advice in this thread?

The problem has been solved, it turned out that the router was running an outdated firmware and also the DNS was not configured properly.