Hello. If you are looking for an alternative to TeamViewer, we need to know about your device. As a universal solution, you can call RemotePC, which has an exciting set of features such as file transfer and remote printing. Also, if you want to share with others on the same screen, you can use the Screens tool for Mac, which supports multiple displays, file sharing, and customizable actions in case of disconnection. And if we're talking about Mac owners, this article at my site includes a complete remote access guide, including tips on setting up the router and troubleshooting possible problems. I am sure this can help you to find the right solution.