: Sorry for the long-delayed response. Have you tried removing the "Trusted" mark in Root Tools and adding it again?
If that's not it, you're going to have to be more specific about the problem. Are you able to connect to the server (i.e. does the browser find the server or does it say something like "the address cannot be found")? Do you get the password prompt? Does the browser connect to the server but get no response? What is the name of the connection (on the phone's screen) that you're using? Are you using the same WiFi network as before (some networks don't permit one device to talk directly to another device; this breaks the way the server works)?
: At *some* point I do plan to implement Chunked data encoding (a form of HTTP transmission that supports large files more easily) or at least handle read-send looping over the file (rather than trying to read the entire thing for a single send). Neither of these are terribly hard, I've just been distracted by other things.
But yes, if you try to upload or download a file that's more than perhaps 50% of your phone's memory (so, 250MB for most WP7 devices) it will likely fail with that error. It may even fail on smaller files. I'll put that fix in the to-do list for once I (metaphorically) get off my but and begin releasing updates to this app again.
A quick note for any WP8 users: Although this app doesn't work on WP8, I've got a new and completely re-implemented version available for WP8. It doesn't (yet) have anything close to full access - it's more akin to fiinix's Mango webserver, but for WP8 - but it does work for some things.
Win8/Windows RT projects:
List of desktop apps for hacked RT devices
Native Access WebServer and Libraries
WP8 Interop Unlocks
XapHandler, Root Webserver, OEM Marketplace XAPs, Bookmarklets collection (Find On Page), Interop-unlock hacks.