|You'll have to excuse me. As a networking professional, I often get caught up on little details like this. It's unusual is all and that jumped out at me. If you read back you'll notice I never said I thought that was causing your problems.....because it isn't. It's just a strange way to configure a highspeed modem to router connection is all.|
As to your actual problem, that's a strange one too. Usually the only thing that causes signal degradation (other than distance from source) is interference, be it physical (ie: walls, metal etc) or wireless (ie: cordless phones and other wireless signals)
I happen to have a bunch of Linksys WRT54GL's in production here where I work and I've found them to be very robust and reliable. If you have no walls in the way and no other wireless signals interfering then you may have a bad router.
I don't know that turning the antenna will help either but it's worth a try. If that doesn't fix the issue, then you may need to replace the router.