Netgear router FVS318 & speed limitations

Hi.

I'm a "newbie" and done some searches similar to my topic but couldn't really find any answers, hence my post.

My small office has a Netgear FVS318 router which was installed and glued to the wall next to the Comcast modem which is then hooked up to our small server.

The modem was replaced with a newer one since our service was increased from 5mb to 15mb download speed.

Can't check the bottom of router without tearing it out, literally, from wall as there are slight variations at Netgear's website so a possible firmware update may or may not be available!

My understanding is that routers do limit the download speed especially if you have >1 computers linked up to the router.

I'm not a tech guy but "jack of all trade" guy in the accounting dept that's good with tech stuff and do whatever I "need" to do but any advance stuff is hired out.

Question : Any methods of "tweaking" the router to "increase" the speed since we're still only getting ~5mb download speed?? It's a pain NOT getting the increased speed when we're paying for it!

Or, is it better to use a Switch instead of a router? All computers have a AV/spyware and software firewall.

Thank you!