I have no idea whatsoever whether this might help as I don't know how RStudio works. But since you seem at a loss, I thought that I would throw an idea out there, in case...
You could try to set
options(help_type="text") in your
.Rprofile and see what happens... Instead of outputting an html to RStudio (in ways that I totally ignore), it might output the help in
less in your console... (that's what happens outside RStudio) and that might be a fix. Or a temporary fix until someone who knows the real answer to your problem can help you. I have never tried to set the help to text in RStudio though, so it might simply not work at all and be a useless idea... (outside RStudio, html help files usually open in your default browser and text files open in the console using
less). Or you might run into the same problem of RStudio looking for a local file rather than a file on the server...