As the documentation correctly states 2097152Kb = 2GB
The POST configuration asks that max size be set in KB it doesn't look like this is the case.
Getting the following error with 250 MB files on Domino console - HTTP Web Server: Invalid POST Request Exception
Tried 0 in the POST configuration which is meant to be unlimited but still the same error
Tried 20971520000 in the configuration and now works like a charm.
Running Domino 8.5.2 x86 on server 2003 FYI - think Domino is reading the setting as B instead of KB