Anti-internet connection aura?

This is the modem integrated router that I'm using. Since goodness knows when (but certainly after the warranty period), it has been going bonkers. It will either suddenly restart itself or just loses internet connection. It does this regularly each day. The frequency per day is sort of random though. The downtime period can range from merely 1 minute to 5 minutes at which point I would manually restart it.

My housemate was away for a few days last week including the weekend. Then a miracle occured: it was sane throughout the entire period! Every single minute for a few days it never once disconnected. As to how I can be sure to the exact minute, I may just elaborate another day.

I also realised that after my Australia trip, during the next one week before my housemate came back from his vacation, the modem also did not disconnect (although I couldn't be sure it was every minute though).

So what do I conclude? I thought perhaps for some odd reasons, the problem exists when my housemate is using the wireless connection. Even he did confirm that if I'm not using the internet and he uses it, it still does happen.

The strangest thing is this: the moment he came home a few days ago, within 10 minutes of arrival and without him even switching on his laptop, the problem occured again for the first time in days. What the hell was that?? It's like he has this evil aura that is affecting it!

I bought a LAN cable to hook up his laptop directly to the modem, based on a friend's suggestion. Didn't work. This is frustrating. Guess I either have to bring it for repair or get a new one but I loathe having to do the installation.