Is this too many devices connected to my router?

So I have AT&T as an internet provider and lately I have been having connecting problems with my router, because my IPhone 5c and Xbox 360 keeps disconnecting. We just had the tech guy set up a new router, but didn't make a difference, so I think its something to do with the amount of stuff connected to my router. Here's a list of stuff connected:

1x HP Pavilion Laptop
1x Sony PS Vita
2x IPhone 5c
1x PS3
1x Xbox 360
1x Verizon Ellipsis 7
1x Dell Notebook
1x Dell Desktop
1x IBM Laptop
1x HP Laptop
2x Nook HD Smokes
2x Kindle Fires
1x Nintendo Wii
1x Roku
Occasionally a Nintendo 3DS too

So that's all the stuff connected to the router, so can anyone tell me if this is the reason I'm having connection issues?

Wow- That may be a new world record.

Obviously, you can't use all at the same time to stream video or do other high demand tasks. Step one would be to turn off all but one. Add back one at a time to see if any single one is causing the problem. However, just t2 devices downloading or streaming data at the s time would create a slow down. Is this an apartment building?

Yes. When you have a lot of devices connect at one time is slows down the connection. You would need a second router or one that can handle that much devices at once.

Most home wireless routers nowadays have 4 LAN ports and a Wi-Fi network. Each of these five connections by default will have an equal probability of getting at your Internet bandwidth. If all your devices are connected to the same Wi-Fi network, they will be sharing a single interface into the router. Also, when there are many devices using a Wi-Fi network, there will be a significant number of occasions when two devices start transmitting at the same time, and they will corrupt each others transmissions. It can be some time before higher level of TCP communications stacks decide that packets have been lost and error recovery has to be invoked. Devices that are using the wireless but are a long way from the router will be slower than devices that are close to the router. In addition, they will tend to slow the traffic for other wireless devices.

If one device is capable of working only in a slow Wi-Fi mode such as 802.11b, then it will slow down the network for other devices.

If the total traffic from your home network exceed the speed your connection to your ISP, then that connection is the limiting factor.

Assuming the Internet connection is not the bottleneck, then a dual band router can help. Each band provides a separate connection into the router. Putting slower devices on 2.4 GHz (older, slower devices probably do not have 5 GHz capability). The 5 GHz band potentially can handle faster connections than the same devices working on 2.4 GHz.

You could also consider connecting devices by Ethernet where they have the capability. Two or three devices connected to a single Ethernet port on the router through an Ethernet switch can be faster (but not always) than the same devices using wireless connections.

You could also consider connecting a wireless access point to one of the router Ethernet ports and setting up a second wireless network for some of the devices. Ideally wireless networks on the 2.4 GHz band should be at least 5 channels apart.

You need to assess the different load requirements of your devices and decide where the bottlenecks are likely to be.

A class C IP address range can handle 253 devices. You aren't close to that. Number of devices not the issue.

Get WiEye on one of the smart phones. It will show you which Wi-Fi channels are used. If your Wi-Fi is sharing bandwidth with a neighbors Wi-Fi, change yours to a channel that is not used.

As for the router itself. Make VERY sure that it is dual band. I would go so far as to make sure it is 802.11ac with Gigabit ports. This is the current spec and the fastest by far. I think the iPhones can use it but am not sure. Don't know about other things. As you replace devices, more and more of them will have 802.11ac. That spec has directional components that make connections much better.

The non moving stuff like the XBox; if at all possible, connect them with Wires. I have a switch behind my TV and it connects the TV, BlueRay, Boxee Box, etc to one Ethernet wire.