Slower than usual D/L Speed on a WIRED connection.

[Nicholas Castellano]

I've had this problem for a long time now and can not figure out what is wrong. I live in a home with multiple computers, routers, and devices. Some are using wireless and some are using wired.

Basic Setup Information:

The modem is on the 1st floor and has an ethernet cable plugged into the wall. This connection goes to the 2nd floor into a "Switch" and then splits to several rooms in the upstairs, my brothers room, the master bedroom, and my own room. In my room, there is a wire that runs across the room to my own personal router. This is a netgear router (very high end and brand new, I had this issue before this router so no.. not the router). The router has ethernet cords plugged in that connect directly to my PC, PS3, and PS4. I also have my phone, tablet, and WiiU connected to this router via WiFi. These devices are generally all shut off and thus aren't sucking up bandwidth from my PC when I have this problem.


PROBLEM:

Most of the time I get speeds of 80Mbps (which is what we're paying for). But then there's some days where I suddenly have internet as low as 15Mbps, but every other computer in the house is running at 80Mbps as they should. I found that whenever my brother used his PlayStation 4 system in the basement on a certain wifi (modem's wifi) it made my internet speed drop. I fixed this, but now he's using a PlayStation 3 upstairs in his bedroom for netflix and I'm having similar issues, so I feel like it might be this. Though I've tried changing the connection on the PS3 and it didn't fix anything.


Attempted Fixes:

I've made a network map, looked around trying to identify a culprit, accessed my router page, accessed the modem's router page. Tried restarting any and every device to fix the problem, but nothing has worked. Late at night, I checked speedtest, and my speed has been slowly getting better. It's currently at 40Mbps, but I was getting 80Mbps for the longest time only a few days ago, so I'm not sure what's wrong still.

Let me know if you need any more information and please help me identify the problem. I've tried static IP addresses but it never seems to fix the problem.



Updates:

6/20/2016: I have disconnected my router and ran a single wire from the wall output in my room straight to my PC. The internet speed is still slow. So this proves that it has nothing to do with my router configuration or any of my own devices (PS3, PS4, WiIU, tablet, cellphone) Also proves that all my internet cords within my room are fine. Internet speed appears to still be slow. It increased late last night from 12Mbps -> 45Mbps, but it's still not the solid 80Mbps that I'm supposed to be getting. Other computers in the house are getting 80Mbps still.

6/20/2016: I have created a network map:

http://i1146.photobucket.com/albums/o533/Nick930/Network%20Setup_zpsyltfjkdk.jpg

I found that if I tried to bypass the Cisco router and plug the cable from the Modem directly into the wall, I lost internet to Nick-PC. How is that possible?!

Solution

6/20/2016: I solved the problem myself. The solution was to restart the "Cisco Router" on the first floor. A power outage must have screwed up something with the router. Still not quite sure why I'm required to use this router just to get internet upstairs. I tried to bypass it using ethernet straight into the modem, but it would not work.

 

[Ralston18]

Check your network adapter configuration. Make sure that it matches the new router.

Especially the speed and duplex settings. Set your network adapter card to manually to match the router - no "auto negoiate" or "auto" settings. However, if manually set, try auto settings. Sometimes devices do not play well together with respect to handshaking requirements.

 

[Nicholas Castellano]

Can you be more specific? Are you talking about my motherboard on my PC? I've already confirmed it has nothing to do with my PC, my devices, or my router. I've plugged a cable directly into my PC from the wall and bypassed my router completely but was getting the same slow internet.

It has to do with something inbetween. Refer to this network map.

http://i1146.photobucket.com/albums/o533/Nick930/Network%20Setup_zpsyltfjkdk.jpg

Note that everything from the Netgear Router and onward is perfectly fine. It's something between the Modem and the Switches that's the problem.

Update: I can confirm that "Upstairs Switch" is not a problem either. Bypassed it with a single ethernet (output wall -> input wall) and have the same problem. So Everything from Upstairs Switch down to Nick-PC is operating normally. It's something else.

 

[Solandri]

If all the other people connected to the same upstairs switch as you are not having a problem, then the likely problem is either your LAN cable, the in-wall cable run to your room, or the port on the switch that your room is plugged into.

Start with the easiest first. Move your room's connection to a different port on the switch. Ports do occasionally malfunction or even stop working entirely. If this is the problem, then just cover the bad port with a piece of electrical or duct tape, so nobody tries to use it again in the future.

Next, try a different LAN cable from your wall jack to your computer. Sometimes one or more of the wires in a cable gets frayed from having a chair rolled over it or being pinched around a corner, and the connection is intermittent.

The last one is actually the most likely, but the most difficult to test (unless you have a network tester). You need to either lug your computer over to the switch room, or get a really long LAN cable. Plug your computer directly into the switch, bypassing the in-wall cable. If that fixes your problem, then the in-wall cable is faulty.

Based on your problem description, my bet would be on the last one. Specifically, the person who wired it in the wall probably mixed up some of the twisted pairs. The two wires in a twisted pair carry opposite electrical signals. At the other end, you invert one of the wires and add the two together. This inversion creates an opposite of any noise picked up by both wires, and adding them together subtracts that noise. But for this math trick to work, both wires need to have traveled almost exactly the same path. That's why they're twisted together.

If someone wires the cable incorrectly (very easy because the proper order is 12356478, not 12345678), the cable still works but the inverse signals travel on different twisted pairs. They don't take the exact same path so the noise they pick up is slightly different. And when you do the little math trick, some noise remains and the ethernet signal is degraded. The symptoms are exactly what you're describing - full speed (or fast speed) when you alone are using the network, degraded speed when someone else is also using the network or broadcasting with a wifi radio. Fortunately this can usually be fixed by re-wiring both ends of the in-wall cable (at the jack in your room, and at the jack or plug in the switch room). Post again once you've confirmed this is the problem and we can give you further instructions on correcting it.

If you still have the problem with your PC connected directly to the switch, only then is it time to suspect the problem lies within your PC.

 

[Nicholas Castellano]

I appreciate everyone for helping. It is a very complex issue with a lot of things that could potentially be wrong. But I did a lot of investigating and have already confirmed that the issue is not in my room. Everything from "Upstairs Switch" and down is confirmed to NOT be the problem. I bypassed my Netgear router and used a single long ethernet cord to plug into the wall and the problem persisted (Therefore, the router can't be the culprit). I bypassed the Upstairs Switch and the problem persisted (therefore, the upstairs switch is not the culprit). I then decided to try something downstairs. I took "Pat-PC" which had perfect internet as it was plugged directly into the modem and plugged it into the "Cisco Router" instead. Immedietly I saw the speedtest results go from 100+Mbps down to 45Mbps. Bingo.. here's the culprit.

So I restarted the Cisco router and waited a while for it to finish booting up completely, and sure enough, got 100Mbps again on "Pat-PC" I switched Pat-PC back to the modem for the sake of returning everything where it belongs and went back upstairs. "Nick-PC" was now at 80Mbps like it should be. The issue was the "Cisco Router." A power outage must've screwed it up and restarting it fixed it.

Now here's the thing that I still don't understand. I tried to bypass "Cisco Router" several times by just plugging an ethernet from the Modem straight to the wall input (the one that connects to the Upstairs Switch), but this makes it impossible to get internet. It's as if i NEED to be plugged into the Cisco Router to get internet upstairs. Why is this? The Cisco Router is just a a router... why can't I get a pure signal straight from the Modem?

 

[Solandri]

Now here's the thing that I still don't understand. I tried to bypass "Cisco Router" several times by just plugging an ethernet from the Modem straight to the wall input (the one that connects to the Upstairs Switch), but this makes it impossible to get internet. It's as if i NEED to be plugged into the Cisco Router to get internet upstairs. Why is this? The Cisco Router is just a a router... why can't I get a pure signal straight from the Modem?

You'd have to talk to the person who installed the Cisco router. It's possible they have a MAC address whitelist on the modem, so only certain devices can connect directly to it. Which could be why they decided to put a router there instead of a switch.

 

[Ralston18]

To answer your question I was referring to the ethernet network adapter on Nick-PC as I understand your postings.

The ethernet network adapter could be either built into the motherboard or installed in a PCIx slot or USB port.

Sometimes different products have problems handshaking to establish communications at the expected speeds. That is why manual settings will work whereas "auto negotiate" etc. may not.

And sometimes the process can take awhile until all of the associated network tables are built.

Agree very much with Solandri's approach and comments with respect to the problem. And your troubleshooting approach as well.

The objective is to eliminate possibilites and/or find a problem follows a particular device, cable, wall outlet, patch cable, or setting.

However, networks can be funny things and stability may not be immediately achieved without some waiting until the all various facets realign themselves.

Actually can be a very complicated process. Look into "Master Browser" sometime. Lots more going one than many folks realize.....