Workstations can't connect to DC over MX84

[Oluwatobi]

I'm using an MX84 security and SD-WAN connected to a 2960 cisco switch. the Win server 2012 is connected to switch which are all on the same subnet. Workstation cannot authenticate and connect to the domain once i connect the MX84 but work well once i change the router to the old cisco 19xx. I didn't set any VLAN on the MX84 i used the single LAN settings.

I will appreciate any suggestion how i can solve this 

[ww]

Can you ping the server?

Did you use the same subnet on the mx as you used on the 19xx?

Did you verify  the arp tables on all devices

[Oluwatobi]

yes i can ping the server and also used the same subnet on the MX just as the 19xx

[ww]

Your Workstation  is also connected to the same switch? Then they should  not even traverse the mx but communicate  directly using the switch. 

[Oluwatobi]

the workstation is connected through wireless and i can ping the server from the workstation.

i tried connecting the workstation directly to the switch with a LAN cable and still can't join the domain when the MX is connected.

[PhilipDAth · Accepted solution]

Is everything in the same VLAN (aka is there a single subnet)?

What is doing DHCP?  Any chance you have two devices doing DHCP (Windows server and MX) by accident?  If the MX is doing DHCP it will need to give out the IP address of the Windows DC as the DNS server.  It should also give out the domain name being used by AD.

[Oluwatobi]

Thanks so much Philip, i noticed both the MX and Window server was doing DHCP. I added the windows server as the name server on the MX and the was able to associate the workstation to the domain.

Thank you.