Laptop wifi interference from screen

neilmcl

I recently had to install a new screen into my dad's Dell Inspiron 3531 (Win 10) after it was dropped. A few weeks later I noticed that the internet was a bit slower than normal and after checking all the usual things with the router etc I still couldn't figure out why speed tests ran from the laptop were constantly showing around 4.5mbps down when the connection speed was over 13mbps and running the same speed test via my phone was showing over 11.

This week I decided to have another look at the screen and removed the bezel and hinge covers and finally the screen and then making sure all cabling was routed correctly and nothing was pinched, all done whilst running speed tests. Sure enough the speed jumped back up to around 11-12mbps and I replaced everything back and it all worked fine for a couple days, but now it's jumped back down to under 5mb and wont go any higher, even though my phone and another laptop can achieve the higher speeds.

I'm at a bit of a loss now and not sure how best to proceed. Do you think that interference from the new screen could be the cause? I did check the actual wifi card was seated correctly and that looked OK with the antenna cables attached fully.

DoaM

Missing or broken screen (earth) wire, meaning the panel is acting like an transmitter?

arciere

No, the screen is what makes the WiFi card receive the signal, it acts as an 'antenna'.

If you opened the screen, you should have noticed two small wires (sometimes 3) that go from the small WiFi card to some metal points in the screen area.

Make sure that they are not damaged or unplugged from the card (the connection is very fragile). Also, if you have more than 2 connectors on the card, check whether you are not using the correct ones.

neilmcl

arciere wrote: »

No, the screen is what makes the WiFi card receive the signal, it acts as an 'antenna'.

If you opened the screen, you should have noticed two small wires (sometimes 3) that go from the small WiFi card to some metal points in the screen area.

Make sure that they are not damaged or unplugged from the card (the connection is very fragile). Also, if you have more than 2 connectors on the card, check whether you are not using the correct ones.

I'm not so sure that's the case. The wifi antenna tabs sit above the screen and as far as I can see the (two) cables are correctly routed. As I said I did also make sure that the antenna cables are correctly connected to the wifi mini card.

I'll try and get up a couple of pics later if that helps.

One thing to note is that although the speed has dropped it still shows a full signal.

neilmcl

Here's a pic showing where the antenna is at the top edge of the display. As I said I've check the cable routing, which comes up from the hinge on the left hand side and all seems fine. Oddly enough, even moving the screen away from the back makes no difference, so I'm not so sure now.



I've got a USB wifi adaptor coming later today so I'll give that a go and see what, if any, difference it makes.

neilmcl

A quick update. I got hold of a USB wifi adapter and tried out that instead, making sure to switch off the main wifi card, and I'm getting exactly the same issue, eg, speed reporting is about half what it should be. I'm a bit stumped now.

abssorb

Start from basics and categorically eliminate all the other aspects of internet speed, to be sure that your recent change is the most likely cause.

E.g. What are the speed test results from other devices on the same WiFi?

neilmcl

abssorb wrote: »

Start from basics and categorically eliminate all the other aspects of internet speed, to be sure that your recent change is the most likely cause.

E.g. What are the speed test results from other devices on the same WiFi?

Every other device, eg, phones, another laptop, are all hitting around 11Mbps down, all using the same speed tester. It's almost as if the Win 10 laptop is capped at 4.5Mbps.

I've also gone through every channel on the router and nothing makes a difference with this particular laptop.

neilmcl

OK, so I believe I've resolved the problem with this laptop now. I ran Malwarebytes and it picked up a couple of threats which I've now quarantined and after rebooting the download speed is now back to normal.

Problem is it's my Dad's laptop and no matter how much "educating" I do he still ends up clicking on all sorts when he's using the internet, I don't know how many times in the past I've had to clean up his computers after they've been infected.

wongataa

Make sure his user account has no admin privileges. Make sure it is a standard user account. This will minimise what he can actually install.


The more extreme option would be to have him use a non Windows device. Does all the software he uses have Linux versions or equivalents?

arciere

What I meant is that the screen area is where the WiFi card gets the WiFi signal from, because that's where the antennas are, so I doubt that it is the screen causing the interference.
I can see that you have fixed the problem now, should it happen again I would try and change WiFi channel (either 1, 6 or 11).