Router/Network issue

[KitchenKitten99]

I have a wireless router from Linksys (model # WRT400N).

I bought it only last year around this time, and have had this same issue since. This is for the whole WiFi and internet system/network at my retail store.

I have the max number of 'ports' set to 100. The POS system (really just a PC with cash register software) is hardlined into the router, but everything else runs wirelessly.

We have 2 Blu-Ray players that have webstreaming capabilities, though they are not used for that very often. We have a Netflix account for those who wish to watch a movie, or they can surf the web via the players.

We also have a wireless printer.

Our internet is Comcast Business Class (so i know it isn't lack of bandwidth, and they have been out a couple times to ensure this isn't on their end)

Here is the issue: If I have more than 4 laptops or other wireless capable devices (iphones, ipods, smartphones, etc) using the wi-fi at any given time, I have problems with webstreaming from Netflix or other sites, and problems printing.

I know it has something to do with the router because when the number of computers or wireless devices is reduced, everything works as it should.

I cannot seem to figure it out.

We also have issues with IP address conflicts. I have started and restarted and reset the router several times with no long-term solution.

This issue also seems to affect wi-fi users who are trying to webstream on their systems if there are more than 5 others connected.

If I have the max ports set to 100, why would this continue to be a problem?

It is not very often that we do have this problem as it is rare we have that many at once using the Wi-Fi. However it is now getting to be more frequent as we get more and more new business customers finding out about our place.

Thanks in advance for your help!