Multiplayer Issues

I, like many others, am having multiplayer related problems. As such, I apologise if this sort of issue has been solved elsewhere; I've done my best to find a solution, to no avail.
Now, onto the issue...
It's not impossible for me to play in multiplayer, I've experienced almost all types of online interaction (haven't dueled a Dragonbro yet though...), however, it's very difficult to do so, especially in regards to joining another host's world.
When it comes to summoning players, around half of them prove to be un-summonable for me. I can try a good 20 times, with no success. In the cases in which I do succeed, it generally takes 3-4 attempts. I've had cases where it's worked immediately though, as well as cases where I've finally succeeded after a good 20 failures.
As for being summoned and invading, I virtually always fail. I can sit around Anor Londo for an hour, and never be summoned (yes, I'm at the right level, and know the best places to put a sign down). In all my time playing, I've only been summoned around 8 times.
Now here's the odd thing. My brother also plays Dark Souls, and he experiences none of these issues to any great extent, easily being summoned virtually everywhere he goes. As such, I can only presume that the issue has something to do with my computer. I don't believe the problem is my firewall, as turning it off changes nothing.
This being the case, does anyone know of any solution? I can work around problem to an extent, but it still is quite a pain at times.
Thanks.

tl;dr: I have multiplayer issues, my brother doesn't. I assume it has something to do with my computer. Any solutions?

I would say that it isn't your computer. I experience the same problems nearly every time i play Dark Souls, and I've found that it just comes down to a bad internet connection. You could try perhaps moving the router further towards your computer, but my computer is also right next to it, and I still occasionally get bad Internet. Some days, I have a decent connection, others can be really bad. So it's kind of a Internet problem, not your computer, to sum it up.

I'm generally the closest to the house's router (and I often use an ethernet cable). As I said, my brother (who also lives here, just for the sake of clarification) has no issues with multiplayer. I don't see how problems in regards to connection would differ so vastly from one computer to another.

Well, as I said, connections can fluctuate, for no reason. I am also right next to the router, and I still get worse Internet than I do upstairs. Sometimes, it's good, and others bad, to repeat my last post.