How to see what devices are connected to my Wifi that is set up with the Time Capsule?

I am not sure what you did in safari.. opening a web page for example at that IP is not going to work with majority of clients.

So you are going to need to do detective work.

1. roll the mouse pointer over the IP 10.0.1.11 and get as much info as possible.. for example MAC address are registered to different corporations.. you can quickly find if the client is apple something or a foreigner. Just google for the MAC address. Go through the list of known equipment and find what is missing from the actual devices on the network in your house.. do not forget printers and other stranger items.. a TV or media player etc.

2. Change the wireless password and listen for screams.. "WHY the internet is not working?" It does not usually take long to then track down one by one all clients with their MAC addresses as you add them back to the network. This is worth recording if you are concerned.. as the Airports are hopeless at showing names.

3. Use a different tool. e.g. Fing or iNet on an iPad or iPhone. There are free versions which are perfectly adequate for what you need.. These tools are FAR and AWAY SUPERIOR to what your Airport Utility shows.

4. Use a real airport utility.. i.e. 5.6 on earlier Mac OS or even windows.. look up the DHCP client lists.

All the useful aspects of the older utility were surrendered to pretty layout in v6 airport utility since Lion.

You can install 5.6 on any Mac OS up to El Capo.. Sierra made much bigger changes and is now not possible. The method is fairly easy but not Apple recommended (after Mountain Lion) and causes issues like sleep not working.. but is still extremely helpful to have log access as well as DHCP client listing.

So here is v6 and v5 running side by side on my El Capo Mac.

One a bunch of pretty icons.. low levels of information.. and the other is a utility.

All the connections to wifi are shown in the airport utility list. Just click the TC in the utility.. a listing of wireless clients is shown (blue box).. hover the cursor over each one and a further detailed info list will appear.. (red box).

If your TC is a flat one.. then you can use a utility like peak hour to discover how much usage is happening from each wireless client.

See https://itunes.apple.com/us/app/peakhour-3/id961578824?mt=12

In their zeal to make apple routers as simple as possible.. it was a piece of functionality removed from the Tall version TC.. !!

Assuming that you have a Mac running a current or recent version of the operating system......

Open Finder > Applications > Utilities > AirPort Utility

Hold down the option key on your Mac while you double click on the picture of the Time Capsule

Wireless Clients will be displayed

Click on the small arrow next to each client to reveal more information about the client

Assuming that you have an older Mac or a PC......open AirPort Utility

Click on the Time Capsule, then click Manual Setup

Click directly on Wireless Clients to reveal more information

Power off the TC

Shut down your Mac

Wait a few minutes

Power up the TC and let it run a few minutes

Power up the Mac and let it run a minute

When you open AirPort Utility, you want to see the Time Capsule appear under the World icon. If the TC still does not appear, then you are likely running Yosemite 10.10.x on your Mac. Would that be correct?

I was able to see the list of clients thanks to your illustration. All the devices have names that I recognize, except one that has 10.0.1.11 as its name. I tried that address in safari with no results. Any suggestions on how to tell what this device is really?