So - at this point, the only errors/problems are solely with the slow wireless on the new MSI, right? [We'll assume that your reinstall fixed everything else] . . .
Questions;
1) What are your speeds when connected directly with an Ethernet cable?
2) Are you running the Intel wireless driver dated October 30, 2015 from the MSI site?
3) Is your router/modem/gateway device from AT&T a dual- band AC device? Or?
4) Does your router/modem/gateway device from AT&T provide two networks -- one 5 Ghz and one 2.4 Ghz?
5) Are you connecting to the 5 Ghz or the 2.4 Ghz?
6) Have you altered any advanced properties for the Intel Adapter in Device Manager?
7) Have you called AT&T and had them check your router/modem/gateway device from their end?
You mention that you are only one meter away from your router/modem/gateway. I'll assume that perhaps a wall is in between? (Since a wired connection is always going to be faster).
When Intel came out with the 3160 ac, some users were having issues like yours in Windows 8 and 8.1 .... here's a link to a thread which advises changing some advanced settings for the wireless in Device Manager. Might help/might not. If the settings help your situation, post that here, and others with the same troubles might benefit.
Very slow download and upload speed on Intel Du... | Intel Communitie
You can also check another "known issue" with your card ... it involves a power-saving component of the driver (uAPSD) --
TechNote: Access Point Interoperability Issue with uAPSD for Network..
See if any of this helps.
[late edit ... am I reading your post right, when you say that on other machines the wireless connects at fast speeds ... but you mention speeds of 1 to 2 Mbps? I'd consider a 'fast' connection to be no less than 20 Mbps ... since many plans go up to 300 Mbps and beyond.... did I misread?]