control internet speed windows server 2012 r2

Solution 1:

Nope, can not do. That needs an enterprise grade firewall - one where the userhas to run a client to authenticate him on the firewall so that the firewall can then figure out his limites based on some policy.

Not only can Windows not do it, most firewalls can not - they purely work on the basis of some sort of IP based scheme. But IP's are at best computers (and can move/change) not user rights.

The old TMG (Thread Management Gateway) could do it - product was retired 2010.

Btw., the setup is odd to start with - you should NOT abuse a server as a router.

The best you can do these days is along the line of putting in a MIkrotik switch and use the acceess contorl mechanism made for wifi hotspots to force users to log in and hen assign them a profile based on group memberships. This login part if critical - as a login is the ONYL way to RELIABLY know what policy to apply to a user.