Networks Is this kind of network possible?

First of all.. i work at a computer shop... (im not a very techie though)
1 isp... 5 ips with each having a 5mbps speed.. as they said..

our original setup is...
modem (4 port) --> linksys Dual-Band Wireless-N Gigabit Router (4port) --> Dlink Gigabit switch (24port)>> then 21 computers.. 1 is acting the time server for the 20 computers..

internet setup is static... since i used 1 of the 5 ip's available.. there's 4 more..
router ip> 172.16.2.1
so all of the computers' gateway is 172.16.2.1..

and then there is an issue regarding the speed of our net.. since it is a shop.. we cant avoid others to download (hogging all the speed).. so a lot are complaining and then im askin myself "why not use 1 more ip of the our isp.. so that there will be more speed"?

what shall i do??
should i buy another router?
and if i have that another router.. what will be the setup??

im thinking like this..

modem port 1>> 1st router(172.16.2.1)>> dlink switch>> 10 computers
com#1 ip is 172.16.2.6 sub 255.255.0.0 gateway 172.16.2.1

modem port2>> 2nd router (172.16.2.2)>> dlink switch>> 10 computers
com# 11 is 172.16.2.16 sub 255.255.0.0 gateway 172.16.2.2

that way.. each 10 computers are enjoying a full 5mbps speed.. instead of 20 sharing it right?

now im asking "is the setup wrong?" why? and what should be the correct?

if it is correct? will there be a network traffic issues?

will the time server be able to see them all?

will the 21 computers be able to see/connect each other in lan games?

please teach me how... im begging you.. lately our shop has been decreasing in customers...

 

172.16.2.1 255.255.0.0 is quite funny subnet to be using for such a small network.

What is the modem?

what service is it? In my office I have a fibre lease line, 10mb with 8 static ip's - each ip does not get 10mb's though, its contested accross the 8 ip's I have. so unless yours are coming in on separate lines you will likely find that is the same.

Does your router have any QoS you could set up?

you internal ip for the router does not have to match you external static ip. they are LAN and WAN. if you on the network search google for whats my ip and that will tell you the external ip which is likely not 172.16.2.1 or you could find it in the router config.

 

If I am understanding you correctly you have an internet service (you call it ISP) and 5 static IP addresses on that service (you call 5 ips)
These IP addresses will share the 5meg service, you don't get 5meg per IP. They are there to allow you to route services on the same Internet connection without the need to set up NAT.
From your description you are only using one, and only need one.

If you need more bandwidth you will need to up your Internet connection, or if it's maxed out, get another installed.
You can then buy routers that will accept 2 ADSL connections (if that is what you have) and load balance them

 

this is what the op needs to do, and is what I have setup here, 2 adsl lines running through 2 adsl Ethernet modems to a netgear dual wan router set for load balancing, I have 13 ip addresses though as I host a few websites and services, including my sbs server.

 

May also be worth seeing if you can get FTTC in your area?