Ping/jitter related to specific computer

[Waerjak]

Hey. I'm new, so I'm sorry if I've posted in the wrong forum. I've got a rather odd issue on my hands.

For the past couple of months, I've been struggling with a slow/unstable internet connection which has been especially noticeable during Skype calls or when attempting to play online games.
As an example, when I am playing League of Legends and my connection is stable (I'll get back to when this occurs later), I will get a constant ~50 latency.
If I'm lagging, however, my ping will be anything between 90 to 500 and this varies wildly, causing issues such as rubberbanding and significantly delayed reactions (more so than 90 ms would suggest.).

So I set about trying to isolate the issue, and eventually realized that my periods of lag were tied to whenever my tenant was at the computer/home. As I came to this conclusion, I decided to experiment a little, and quickly found out that if I simply blocked his computer's mac address the issue would instantly be fixed. Obviously this is hardly a long term solution. In fact it's no solution at all. Hopefully you guys can help me figure out a way to get rid of this weird issue.

I have full access to the router, but unfortunately can't say the same about my tenant's computer. If there is a solution that involves him then I can talk to him about it, but he wouldn't likely allow me access to his computer without serious evidence.


The router is a ZyXEL P-2602HWT-F3 running firmware updated to V3.70(ASC.9).
I'm connected by Ethernet cable. The tenant is wireless. There are also at times more than 5 computers connected to the router by various means, but only blocking this specific tenant's computer results in a fix.

Here's an example of what my ping looks like when I'm not lagging:
http://www.pingtest.net/result/77788313.png

And here's one where I am lagging:
http://www.pingtest.net/result/77713334.png

The odd thing is, I can be lagging even when the pingtest shows results like these:
http://www.pingtest.net/result/78060894.png

Thanks in advance.

 

[PhilFrisbie]

It sounds like your tenant is using software that saturates your Internet bandwidth.

 

[wacabletech]

So there are a few missing pieces of data.

What speed do you subscribe to? If your on 768Kb dsl there is not much hope in reality.

What is the tenant doing exactly? Maybe he is just using an app he does not realize or is a spambot?

Are you looking to spend money to fix this, if so you can buy more expensive routers that have bandwidth control features so that you can limit the total bandwidth each connection is guaranteed. IE if you pay for say 6Mb service you could say each can only get 3 so that one does not cripple the other by taking 5.5Mb up.

 

[Waerjak]

I'm supposed to have 5 Mbps down and .5 Mbps up. I would prefer to avoid spending money to fix it except as a last resort.

If I knew what he was doing exactly I probably wouldn't be having this problem. He's not exactly computer savvy so it's entirely plausible he's installed some sort of app that drains the bandwidth...
I'm just hoping there's a way to do this on my end of things before I go poking in his private laptop looking for weird programs or malware, as I don't think he'd know what to look for (unless he does and I've been a fool for thinking it's accidental). Even if justified it seems like an invasion of his privacy.