Aspia - free open source application for real-time desktop remote control and file transfer.
With Aspia, you can create your own NAT traversal infrastructure (using Router and Relay servers) with connection by ID or use direct connections. Aspia supports many features. Among them, detailed information about the system, audio, text chat.
Aspia is a free project for end users, but there are some costs to maintain it. If you have the desire and ability to support the material existence of Aspia, then you can do it.