Internet Speed Fluctuates Up and Down on a LAN Network

I'm with Tom.  We need more details.  It could be a firewall doing it, a router, a switch, computers on WIFI instead of LAN, anti-virus, a server with something not configured correctly, more employees coming in and running at capacity, a patch on a computer, the browsers.

Give us details with for instances, when it happens, what the logs show, etc.

Esteban

Do a tracert command to any website, for example http://microsoft.com to obtain network info (device IP's)

From different endpoints on your LAN, for example one from the server and another from a workstation. Do ipconfig /all to verify the default gateway (will show up in tracert as well).

As you get the info from tracert use ping -t <ip address) for each step along the way. You don't have to do one all the way to Microsoft but you do need to include your router, the device inline from your ISP (you'll see this in tracert) and watch for the ping to increase above time=<ms, you will most likely see it increase well over 500ms.

Make sure to include the switch on your network and I would reset it since it's a single point of failure and if it's a managed check the logs.

Also include the server NIC, router IP, and the device from your ISP downstream from your router each separate with it's own ping -t <ip address>.

Do you have VOIP and a secondary company providing your internet? They all use Time Warner or some provider and often over utilize bandwidth compromising end user speed to make money on their end.

What ISP are you using?

We are a small LAN running Windows 2008R2 on 3 servers of which only one is a domain controller, the PDC. Each server is running 1 or 2 Hyper-V VM's.  We have Comcast business internet 53 m for an ISP. Connects with one of their cable modems through a Cisco router connected to a Cisco Switch. We run Symantec Endpoint 12.0 for our AV and firewall service. The company operates from around 7AM til 5PM every weekday and it's been like this for a couple of weeks at least. We are doing random internet speed checks with Speakeasy speed tests. Right now, it seems fine:

9:37 AM:
Your Speed Result:
Download Speed: 57083 kbps (7135.4 KB/sec transfer rate)
Upload Speed: 9498 kbps (1187.3 KB/sec transfer rate)

9:39 AM:
Your Speed Result:
Download Speed: 35458 kbps (4432.3 KB/sec transfer rate)
Upload Speed: 10879 kbps (1359.9 KB/sec transfer rate)

9:41 AM:
Your Speed Result:
Download Speed: 22199 kbps (2774.9 KB/sec transfer rate)
Upload Speed: 10905 kbps (1363.1 KB/sec transfer rate)

9:44 AM:
Your Speed Result:
Download Speed: 40195 kbps (5024.4 KB/sec transfer rate)
Upload Speed: 10351 kbps (1293.9 KB/sec transfer rate)

Never stabilizes. Not sure if we have streaming issues with our users(60 or so) or maybe we have something just not quite set up right in our network. Comcast says all is well on their end, but I have my doubts. We have no Wifi running at all.

Where you able to get any answers from Comcast?  I wanted to check in and see how things are going.

It was the ISP Comcast, they stated that our modem wasn't capable of keeping the max 50 mgs and determined there were problems at the main pole

So when I suggested in my initial comment that I didn't always believed it was the ISP and it ended up being the ISP the problem, why were the points not awarded to me?

I'm not looking for points however for learning purposes if you would have done a tracert as mentioned in post ID: 39774086 then ran a constant ping to each end point you would have seen the problem was outside your network which you could have then shared with your ISP.