wireless Users WLan Maximum Clients

how much users does the wireless support
How to support more than 500 users at one time on a WiFi network
How many can current wireless users can support?
How many simultaneous users can my WiFi network handle?

the maximum amount of users that may connect via WiFi is 256 (including a server and router) with the subnet mask Changing the subnet mask may increase the amount of users but in reality more than 20-30 would halt the router.

The more devices that are simultaneously connected to your device, the slower the transfer speed will be for each device. D-Link recommends 15 simultaneously connected users as the maximum number.

Can it be solved via multiple access points? I mean one router and 3-5 or more access points?
YES, that would be the normal way to do it. AP's are limited to a maximum number of clients due to wireless protocol limits, however routers scale much higher, so 1 decent router will be sufficient for 500 users. Number of AP's depends on the actual AP(s) you buy.
You can get around these limitations by adding additional routers or access points:

How to Maximize Your Network's Potential

Installing a second router or access point on a home network can greatly help distribute the network load. By adding more access points to the network, effectively any number of devices can be supported. However, this will make the network progressively more difficult to manage.
Most home-routers stop at round 30 users (dual band Netgears at 64, etc..) and you will have to make a routed network with more that 16 access points to make your server available.

If you want to support up to 100 users and have something usable, you'll probably want to set up 3 access points throughout the building. Personally, I'd do more, but using more than 3 APs in close quarters can cause problems that you may not want to cope with.

For a MT solution, I'd get the RB750UP, and use that to connect and power up 3 of the RB951-2n access points on channels 1, 6, and 11, which will keep the self-interference to a minimum.

One access point can support a high number of clients, if the devices are near by. This is the case for HD or High Density access points some vendors offer. They have a little more memory and a better processor, but the main difference is in the antenna design. The antennas are designed for short range. If all the devices are within the same conference room they can all be connected at 300Mbps at least. The air time can be split into very short slots so everyone gets a share and still have useful bandwidth. These APs are designed to prevent connections from outside the room because those would be slower. You can place multiple HD APs in a large auditorium if necessary since the coverage is designed to be small, at least if you turn the transmit power down.
You can use a couple of dozen of devices per access point as a rule of thumb. If you are designing for a high capacity network, use more APs and smaller cells. There will be less devices in each cell and each one will have a better connection. Both will improve the capacity of the network on its own and together they complement each other. It is a win-win and the cost of modern APs makes this affordable.