Question Why does my internet connection drop when using DisplayPort cable?

madmanfame

Novice Member
So i've just purchased a new monitor and a DisplayPort cable to use G-Sync.

Unfortunately using the DP cable kills my internet connection. Download speeds are terrible and, due to the lag, it's virtually impossible to play games online.

Everything's fine when I use the HDMI cable. But of course to use G-Sync (which is a must for me) I need to use the DP cable. So this is really irritating.

So what's the crack here? Anyone experienced anything similar?
 

next010

Distinguished Member
That is truly bizarre, I've never heard anything like that before.

I would try disabling the network adapter that is in the PC (disable at bios level if it's built into the motherboard), borrow/get a USB ethernet or WiFi adapter and see if the problem persists with that.
 

madmanfame

Novice Member
I've sorted it, but haven't determined the exact cause of the problem.

TL;DR
When the WiFi card or WifFi dongle is installed at the back of the PC -- within 10cm of the DP Cable -- the WiFi connection plummets or simply doesn't work.

When the the WiFi dongle is plugged in at the front of the PC -- away from the DP Cable -- the connection is fine.


borrow/get a USB ethernet or WiFi adapter and see if the problem persists with that.
So yesterday this is exactly what I did. I picked up a cheap USB WiFi dongle to see if the problem was with my WiFi card. (I'd been in touch with the cable manufacturer and they insisted that the problem couldn't be with their cable, that instead it must be with my WiFi card.)

I first plugged the WiFi dongle into the front of the PC. Within 20 seconds it connected to my router. I then tested the connection by streaming some video, downloading some files, and playing some online games. Everything was swift and stable.

I then took the WiFi dongle and plugged it into one of the rear USB ports. These are within about 10cm of the DP Cable. At first it connected without any issues. After about 30 seconds however I started to notice the same old problems. Videos started to buffer or wouldn't load at all, and download speeds plummeted to negligible levels. Before I could even test an online game the connection had been lost, and I was subsequently unable to reconnect to the network. This confirmed that the issue wasn't with my original WiFi card, and that it must have something to do with the WiFi receivers being in close proximity to the DP Cable.

So what's the exact issue? I still don't know. Again, my hunch remains that -- as weird as it sounds -- the cable must be faulty. Either that, or there's an issue with the GPU. All three DP ports produce the same results though, and everything is fine with the HDMI cable, so i'm still inclined to think the issue is with the DP cable.

I suppose the next step is to test another DP Cable, one from the same manufacturer and maybe one from another. If the results are the same then I guess the issue must be something internal...
 

techquest

Well-known Member
As @next010 has stated, it is bizarre. I've never come across it and was doing some research into it and have found nothing remotely like it.

As for the cable manufacturer, they would say it can't possibly be their cable. But I would have to suspect that it is the cable. As you say the only way to prove that is by using a different cable, though you only really need to buy a different one to prove the point. If you buy from Amazon then you can always return it if not needed.

Let us know how you get on please.
 

madmanfame

Novice Member
Interesting update.

Yesterday (for a totally unrelated reason) we received a new router from our ISP. It's dual-band so i've been able to take advantage of the 5GHz capability of my new WiFi dongle.

No matter where I plug it in -- at the front or near the DP cable at the back -- the connection is strong: consistent download speeds of 36/37mbps.

However, when I connect to the 2.4GHz band on either the dongle or the WiFi card, the connection plummets.

So this narrows it down somewhat, although we're still left wondering what the exact problem is. Why does using the DP cable cause problems on the 2.4GHz band but not the 5?

As you say the only way to prove that is by using a different cable, though you only really need to buy a different one to prove the point. If you buy from Amazon then you can always return it if not needed.
Although i've found a way around the problem, I think for the sake of just knowing what the problem is i'm going to pick up another cable.

I'll keep you posted.
 

Peeej

Member
I had a similar issue with a mouse nit internet related but, if I had the dongle in the back of the machine or the front the mouse would stutter, if I moved it to a hub it is fine.
The problem is apparently cause by the CPU frequencies, certain frequencies effect the dongle if too close.
I wonder if this is a simialr thing even tho the cable must be shielded
 

techquest

Well-known Member
Interesting update.

No matter where I plug it in -- at the front or near the DP cable at the back -- the connection is strong: consistent download speeds of 36/37mbps.
Assume your talking about plugging in the Wifi dongle?

.
However, when I connect to the 2.4GHz band on either the dongle or the WiFi card, the connection plummets.
So from what your saying here, you have a Wifi card in a slot on the mobo and a Wifi dongle ?

So this narrows it down somewhat, although we're still left wondering what the exact problem is. Why does using the DP cable cause problems on the 2.4GHz band but not the 5?
It really is an interesting one. I recall dealing with something on an issue with dongles a while back and as @Peeej is saying the dongle might be an issue and might be better plugged into a USB hub, it was a recommendation I suggested having done some research on the issue at that time.

Although i've found a way around the problem, I think for the sake of just knowing what the problem is i'm going to pick up another cable.

I'll keep you posted.
Yes if it was a problem I was having I would also want to know if it was the cable.
 

madmanfame

Novice Member
So I picked up another DP cable.

To my surprise the results were exactly the same.

Connections via the WiFi card (plugged into the motherboard @techquest) simply don't work. Most of the time it just can't connect, other times when it does the download speeds are atrociously low.

Connections via the WiFi dongle on the 5GHz band remain perfect. Easy to connect and fast download speeds.

However, since my last update I am now able to connect to the 2.4GHz band via the WiFi dongle even when plugged into the back of the PC and irrespective of which DP cable I use. Download speeds when the dongle is plugged in at the back are around 7-8mbps, whereas at the front speeds are usually around 20mbps. This seems to suggest that the issue concerns the proximity of the WiFi device to the DP cable: the closer it is, the worse it performs, with some performing worse than others.

It could also be that @Peeej is onto something with the cpu frequencies. Because it isn't just the DP cable that the card and dongle are next to, it's the cpu as well.

The only thing I am certain of now is that the original DP cable isn't faulty, but it is the using of the DP cable that is causing the issue with the connection.

I'm not sure where to go from here, but i'd like to get to the bottom of it. Anyone got any suggestions as to what I should test next?
 

techquest

Well-known Member
You can get double shielded types for optimal reduction of electromagnetic interference. So what type of DP cable are you using, whose is the manufacturer and version?

Might be a solution but no promises.
 

madmanfame

Novice Member

Jimjam1234567

Novice Member
Hi, did you ever find a solution to this?
I just bought another monitor and I’m running into the exact same problem! every time I plug in the display port cable my internet instantly drops and I am then unable to connect to my network.
Many thanks :)
 

madmanfame

Novice Member
Hi, did you ever find a solution to this?
I just bought another monitor and I’m running into the exact same problem! every time I plug in the display port cable my internet instantly drops and I am then unable to connect to my network.
Many thanks :)
Nah, to be honest I couldn’t be bothered in the end! But even though I didn’t get to the bottom of what the problem actually was, I was still able to get around it. So if you haven’t already I’d recommend just trying out some of the stuff I did (moving dongles, changing bands etc) and seeing where you end up.

Not sure if this is relevant but a few months ago we got Sky Q installed and hooked up one of the mini boxes next to my setup. If you’re not aware the mini box receives its signal for TV and downloads and stuff from the main Sky Q box in the living room. It also serves as a WiFi booster. Interestingly whenever this was powered on and near my PC, rather than improve my connection it actually crippled it! Games like Rocket League became totally unplayable because of the crazy ping I was getting. Move the mini box away or turn it off though and everything would go back to normal.

So I dunno, maybe my rig is super sensitive to certain frequencies or something (I’m not knowledgeable enough to say with any certainty!). Maybe this is what you’re experiencing as well?

Anyway hope this at least kind of useful. I know how frustrating it is so I’m happy to answer any more questions to help you get to the bottom of it 😊
 

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