Internet slows to 50% through a router

kenlotterman
kenlotterman used Ask the Experts™
on
No matter what router I use, I only get 30 - 50% of the internet speed through it.

If I connect a laptop directly to the Comcast modem, which is in "Bridge mode" so that the connected device gets a public IP address via DHCP, I get about 100mbps.  If I connect a router BETWEEN the modem and the laptop, the speed falls to 30-50.  There is NO OTHER device connected to the router or the modem.  I have confirmed this problem using a SonicWall TZ400, a Cisco RV180, an ASUS RT-N12, and a UTT ER518.  The issue remains for each of those routers.  I also used the same patch cables for each measurement.  Wireless is not involved.  

Why does this happen and how do I change it?
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Blue Street TechLast Knight
Distinguished Expert 2018

Commented:
Hi Ken,

A TZ400 should provide you with 300 Mbps of throughput full configured with all inspection and Security Services.

A computer connecting through a wireless connection is going to natively process slower than a wired connection...for example when I test at some sites with 100x100 on the desktop I get that but on the laptops I get about 60-80Mpbs.

There are a number of factors at play here. Wireless technology is completely different then wired. Wireless drivers, interference (digital & physical) come into play as well.

Let me know if you have any questions!
JohnBusiness Consultant (Owner)
Most Valuable Expert 2012
Expert of the Year 2018

Commented:
I do not have an answer at this point, but I am watching this.

I have a Rogers Hitron Modem in Bridge Mode and a Cisco RV325 VPN router attached to that. Burst speed is 80 Mbits/sec for some seconds and then I get my rated ISP speed of near 40 Mbits/sec.   No slowdown. The RV325 has 900 Mbits/sec internal throughput and your RV180w says it has 800 Mbits/sec which is the same generation and speed as my (retired) RV042G router.

Are you using CAT 6 Cables?
Blue Street TechLast Knight
Distinguished Expert 2018

Commented:
Make sure your SonicOS is at the current General Release too.
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Natty GregIn Theory (IT)

Commented:
A few things either those devices are failing or your cable needs to be replaced or the or those devices do not have enough power meaning processing power to produce the given speed. I choose the latter because I had similar issue changed my modem to an AC modem with 2gig processor and now I'm getting the speed I pay for --I'm even getting 100mbps over wireless
Blue Street TechLast Knight
Distinguished Expert 2018

Commented:
I'm not going to lookup all the devices but I have to give the OP the benefit of the doubt that they verified the benchmarks. I know for a fact the TZ400 has more than enough processing power fully load running a full sec stack to process 300Mbps...and the fact that the OP is getting the same results with that many different devices makes me think maybe something is governing your connections to those networks.

Can you try a different device and use the same wired connection method?

Also test with a different CAT 6 cable.
Natty GregIn Theory (IT)

Commented:
We are all here to help -- so try the suggestions a see which one works

Author

Commented:
My bad - apparently I got distracted when responding to Natty Greg's comment.  I tried different cables and still no difference.So, just for grins, I took the Comcast modem OUT OF bridge mode, configured the NAT/DHCP, disconnected the SonicWall router, and connected my network switch directly to the Comcast Cisco modem/router/wireless.  Now I get a speedtest.net result of 77, which is far better than before (but still not the 150 I am paying for).
Blue Street TechLast Knight
Distinguished Expert 2018

Commented:
It sounds like an issue with your Comcast modem since you are able to duplicate the same results every time no matter which firewall you add. You may need to request a new modem and an onsite tech from your ISP. They should bring a new modem with their visit.

Between testing are you power cycling the Comcast modem? Some Cable Modems can bind to the last known Ethernet MAC address. Make sure you marry itself to the new MAC address of the firewall you are testing by connecting it to the new firewall, disconnecting the Comcast modem's power adapter, letting it sit for a couple of minutes, reconnecting power, and waiting several minutes for the Comcast modem to initialize.

Run ipconfig /all and make sure you are receiving the correct IP info then ipconfig /flushdns, ipconfig /release, and ipconfig /renew.

And so again for clarity you are plugging into the modem with a wired connection testing internet speeds and then disconnecting from it and adding a firewall downstream from your modem then plugging into the newly added firewall with the same cable and retesting? Does this some up your testing method?
Distinguished Expert 2018

Commented:
Without repeating the previous suggestions, I would make Comcast test the lines since you're reporting getting 100. That's already an issue right there, as you should have at least sometimes been hitting 150. Which site are you using for tests anyway? I encourage you not to use the Comcast speedtest site as you are seeing results to a point on their own network.

Also, is the public wireless feature disabled?

If this is a business line (which is what I am assuming you have), try getting a replacement gateway. If residential, get a modem only unit.
Ehigbai IyemifokhaeSenior Core Infrastructure Engr

Commented:
This is possibly high CPU. Please can u check what is eating up the cpu

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