I read over your email and will do my best to help you.
Let’s begin with the smaller branch supporting the five user workstations and the very slow network connectivity. You may not need a DNS server at all. If there is a lot of file & data sharing, then maybe the branch could benefit from a server, but configured in a secondary zone, such as an ADI. If there is not enough file/data sharing to need the presence of the server, an ADI server could potentially slow down an already sluggish system even more.
For the second much larger branch, supporting around thirty users with a much better network connectivity; I would recommend a DNS server set up in the primary zone. I would also suggest moving your servers from the smaller branch to your larger branch. All files from the smaller branch could be accessed via a “VPN” remote link. This would allow the smaller branch the ability to use a much smaller router, which might help with the connectivity problem the users have experienced.
Sincerely,
I’ve read over your email and am going to do everything in my power to help you. My first question is what have you attempted to resolve the issue? Start by checking the DHCP setting and configurations and make sure they all correctly configured. Try renewing the IP addresses on the workstations that did not pick up the new leases from the scope it might have something to do to with the IP lease agreement. The Lease period for your DHCP is 8 days for wire and 24 for wireless. So machines will not request a new IP address until this lease expires.
If a Machine reboots, it will ask for a new IP address from the DHCP, so I think the few machines that received new IP addresses from the new scope were rebooted. Also check the event log and DHCP server log files for details on any problems. Make sure the address scope has enough addresses if not widen the scope range. Check to see if it is a router/firewall problem and makes sure you