I'm looking for a way to transfer files between an Android phone (Samsung Galaxy S2, rooted) and any computer system I may need to interact with (this means preinstalled software on the computer, besides a regular web browser, is not an option) without connecting to an actual WiFi hotspot.
Essentially I'm looking for something that works the same was as WiFi direct (allows two phones to transfer files over WiFi) but that would be compatible with any computer with WiFi.
So far I have tried creating an ad-hoc connection from the phone (as I can't take the computer being ad-hoc-creating-able for granted) using Android WiFi Tether and connecting the computer to the device, testing the different modes it offers (WEXT, Netd & Softap). I have tried to connect to and from the computer over LAN, FTP and SMB without any success.
I feel like I'm missing some small step over here. I've looked through multiple other posts, but I couldn't find any that would show a way to do this without actually connecting to an already available wifi network.