Radmin. Always works, no internet connection required. Costs $US49. Been using it for years without any issues.
https://www.radmin.com/download/
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About Radmin
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Radmin is fast and secure remote control and remote access software that enables you to work on a remote computer as if you were sitting in front of it and access it from multiple places.
Radmin consists of two modules:
* Radmin Viewer needs to be installed on the local computer (for example your home PC or notebook) which you want to use to access your remote computer.
* Radmin Server needs to be installed on the remote computer (for example your office PC) that you want to access from your own one (for example your home PC or notebook).
To get started make sure Radmin Server is running on the remote computer. Then run Radmin Viewer on the local computer and connect to the remote computer.