I don't think there is such limitation. Do you have different VPN account and password for 2 desktops? Any error message when 2nd one disconnects? You may test the 2 desktops with other router.

If the password you referred to is the cloud password before you configure the device, you can find the password according to this FAQ. http://www.tp-link.com/us/faq-802.html If it is the wireless...

Thank you for your sharing. You may feedback to TP-Link support.

A new firmware was released today. You may have a try. Problem Solution

You may try to reset it and reconfigured it. Besides, a new firmware was released today. Please the new firmware first.

Do all devices connected to C59 have no internet access or just some of them? You can reset the router by pressing the reset hole for 10-15 seconds until all lights become flashing. If the firmware...