For remote control / file transfer only? teaviewer is expensive because of all the other sillyness it does.
I use https://www.msp360.com/remote-assistant.aspx as it is free for commercial use and very very hard to block.
Encryption is not enabled by default but easy to flip on. If you are already using some sort of password manager, no big deal. View only is the default setting so dont forget to flip that bit.