Make sure each LW is using a different port. You can check via Tools > Options > Advanced > Firewalls.

You will notice the limits of wireless connections when you are downloading heavily. Wireless is known to be unreliable speeds, and some models of router may drop connections. You may have too many connections attempting to connect at same time which is giving the router headaches. You could consider Tip: Purge the Downloads Queue! (click on blue link)

You could also consider disabling both OOB (under speed options) and also disable the Performance options under Tools > Options > Advanced > Performance.