I’ve been all over the map about QuickBooks requirement to map a network drive in a QuickBooks multi user setup. For awhile, UNC paths were the way to go. First it was \\[server name]\[share name] not mapped, then \\[ip address]\[share name] not mapped. Now it appears that we’re back to mapped drives.
Straight from the source, Intuit spells out QuickBooks curent thinking about mapped drives below.
The take away: Do it by the book, there must be a good reason.
I’ve learned from experience that when picking a drive letter, choose something above LMNOP and make it the same for every computer accessing QuickBooks.