Cannot connect to JET unless I use IP?

So I’m in the process of upgrading to NAV 2013 and so far everything is working well. The only issue I’m having is making my JET connection settings function. If I input the IP into my browser, it asks for my credentials and then displays the XML output. If I put the server’s NetBIOS name in place of the IP, I get an “Error 400”. Now I know this sounds a lot like a DNS issue but I can assure you it is not DNS. I can ping the server by name without issue.

I’m pretty much out of ideas at this point and am very close to throwing in the towel and just using the IP address in my connection settings. This really sucks as I want to create a DNS record with a generic name so when we upgrade again, I don’t have to worry about changing the JET settings on 60 terminal servers.

Any advice would be greatly appreciated.

OK, I resolved my own issue. It turns out there is a file called Customsettings.config that sits in “C:\Program Files\Microsoft Dynamics NAV\70\Service”. There is a line in the file that reads “”. By default, the value is set to “false” which does not allow NTLM authentication. Simply change it to “true” and everything works great.

I have a hard time believing I’m the only person to run into this issue but I hope this post might help others at some point.