Xbox One creating a new device each time it starts on the same network PCs

Don't see how this actually would come as a problem...

Anywho, try go into the Settings of your console and Preferences and make sure 'Allow game streaming to other devices' is unticked.

Don't see how this actually would come as a problem...

Anywho, try go into the Settings of your console and Preferences and make sure 'Allow game streaming to other devices' is unticked.

It partially worked... For Windows 8.1 I don't get the device after I unchecked the Allow Play To streaming option. But on Windows 10 I still get the device (even with Allow Play To streaming & Allow game streaming to other devices unchecked).

As for why... It is not really a problem. It doesn't seem correct behavior (and I blame Windows for that) to just create an endless amount of devices.

You can't . Once you disconnect you need enter the password again.

Xbox One doesn’t save old device information, allowing you to completely wipe out old settings and start new each time. This saves you from accidental manual entries that could cause issues on a new network.

http://support.xbox.com/en-US/xbox-one/networking/network-settings

Other reasons for other devices to drop off the network at the same time might be if a static IP is set on your Xbox or other devices creating a ip conflict. All devices should have a different up address, on PC this can be seen under status > details under
your WiFi or Lan connection.

Another network drop out related issue can be created from what is known as a loop in the network, most new routers are designed to detect this, and stop the loop. A loop is where a network point connects from one network point into another network point
on the same device, it create a snowball effect of data communication, and causes the device to hang.

I have seen some modem / routers that offer USB connection instead of network, where plugging both to a device would also cause it to hang.

if you are using adsl or adsl 2+ you also need to make sure all phones / faxes connect to your phone line are connected to a adsl splitter, this filters the signals sent on the line so that the phone line is not disrupted by the phones. This can be tested
by unplugging all phones and faxes from the line, then testing your equipment to see if it drops your network.

But in general if your network is dropping out with two many devices attached it is likely your router simply can't handle the quantity of devices connected.. You should also see a performance increase to your internet with a new router. You may also need
to contact your internet service provider for details on how to configure the new router for your internet connection.

once replaced, each device will need to be joined to the new router.

Best of luck.

At a time one controller can be synced only to one console/PC. But you can always switch between the devices by syncing the controller each time with the new device.