If your connection is that good & you're finding results ok then I'd be a bit suspicious of the ISP. If you want to try changing ports, go tools > options > advanced > firewall config. You'll see LW's listening port in the top right corner of the page. You can change that to either the port number your brother's using for uTorrent (he should be able to find out what port he's using) or try a port number between 49152 - 65535. Change the number & apply to save the change.

Are you forwarding a port through your router? If you are, then you'll have to change the port number you used within your router configuration & also change the port number chosen in the 'manual port forward' option on that same page with the listening port number. If you're not port forwarding then don't worry about this bit.

Now also change the port numbers allowed within your software firewall (you would have had to set that up when you first started using LW). All the port numbers you use should be the same as the LW listening port.
There's no guarantee that this will work, but it does for some people.