Hosting the files from Server would be much safer for you. It sounds like you currently have the file on a shared drive/directory where the first user opens it directly and then subsequent users use Open Remote to access the database. This risks corruption of your database file that will be avoided if it is always opened first on the same machine as where the drive is installed and then all other users use open remote.
I don't see, off hand, how this change will affect the ease with which users can access the file from an off site location. Those issues could, in fact, be due to internet connection issues specific to their off site locations and not the hosting method you choose to use.
Since you have been using a shared location, I'd run a recover on the file to see if it reports any problems. Sometimes file damage will be tolerated by one platform and not another, so this is a possible explanation as to why it is just the Mac users that are having trouble.
Things to keep in mind about Recover:
- Recover does not detect all problems
- Recover doesn't always fix all problems correctly
- Best Practice is to never put a recovered copy back into regular use or development. Instead, replace the damaged file with an undamaged back up copy if this is at all possible. You may have to save a clone of the back up copy and import all data from your recovered copy to get a working copy with the most up to date information possible.