DHCP not always handing out DNS Server to Clients

Question

Hello!

I apologize for my ignorance, I'm new to the Q&A forums and I'm self taught in Servers, so there's a lot I don't know but I've been working with them since SBS03 so there's a lot i do know too.

I know there's many bad practices at work here, but please bare with me!

I have a single server that does everything (here's where you cringe), it has the onboard NIC that i'm using for my VM's, then i have an addon NIC with 2 ports for LAN and WAN. I'm using RRAS to share internet from one NIC to the others, and to route the appropriate traffic to some devices and the two VM's i have (mail server and plex server). This is a home server running Windows Server 2019 Datacenter (i <3 Microsoft Imagine). I'm using AD for accounts, group policy for restrictions, I have a Synology NAS for shared folders across the network and a Zyxel NAS. Server runs DHCP, DNS (cringing yet?), AD, Hyper-V, IIS (which i should probably remove since all web traffic is sent to the VM's and the Synology NAS), and RRAS.

My LAN adapter has IPv6 disabled (in fact, everything IPv6 i can find is disabled but it still hands out IPv6 addresses), and is configured like this (ive replaced my domain with *):

Connection-specific DNS Suffix . : *.local
Description . . . . . . . . . . . : Realtek PCIe GbE Family Controller #2
Physical Address. . . . . . . . . : 00-E0-4C-69-1D-5A
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes
IPv4 Address. . . . . . . . . . . : 192.168.16.2(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 0.0.0.0
192.168.16.1
DNS Servers . . . . . . . . . . . : 192.168.16.2
NetBIOS over Tcpip. . . . . . . . : Enabled

A couple things that concern me here; 1) It says DHCP is not enabled, and 2) The first gateway is 0.0.0.0??? It doesn't show that in the adapter properties for IPv4

Ok so then here's my WAN configuration (my IP and gateway is replaced with x.x.x.x, its a static IP)

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Realtek PCIe GbE Family Controller #3
Physical Address. . . . . . . . . : 00-E0-4C-69-1D-59
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes
IPv4 Address. . . . . . . . . . . : x.x.x.x(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : x.x.x.x
DNS Servers . . . . . . . . . . . : 8.8.8.8
8.8.4.4
NetBIOS over Tcpip. . . . . . . . : Enabled

This is essentially the settings provided to me by my ISP, and internet works flawlessly on the server.

Server is setup as a domain controller and a few weeks ago i moved everything from my old server to a new one, and the old one is off. I've had MANY problems because i did this terribly wrong, but I'm now down to my very last issue. Sometimes when i connect to a router, everything works fine, but other times there's no internet. However, if i go and take that connection without internet and add my domains IP address as the DNS server, suddenly everything works flawlessly. Looking at each connection, when it works i can see that a DNS IP was assigned (192.168.16.2), but anytime internet isn't working, no DNS was assigned.

This completely happens at random! I'll connect my phone to the access point and it works, but the next day it doesn't work and everyone elses phones work, and every combination there-in.

Here's what the WLAN configuration looks like when it fails on one of the client computers (again, domain replaced with *):

Connection-specific DNS Suffix . : *.local
Description . . . . . . . . . . . : Intel(R) Dual Band Wireless-AC 3168
Physical Address. . . . . . . . . : 34-7D-F6-FC-64-B7
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
Link-local IPv6 Address . . . . . : fe80::75d2:d03c:253f:1757%13(Preferred)
IPv4 Address. . . . . . . . . . . : 192.168.16.72(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Lease Obtained. . . . . . . . . . : Wednesday, December 16, 2020 12:38:28 PM
Lease Expires . . . . . . . . . . : Wednesday, December 23, 2020 12:38:27 PM
Default Gateway . . . . . . . . . : 192.168.16.2
DHCP Server . . . . . . . . . . . : 192.168.16.2
DHCPv6 IAID . . . . . . . . . . . : 154435062
DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-27-12-3C-06-2C-F0-5D-78-49-E0
DNS Servers . . . . . . . . . . . : fec0:0:0:ffff::1%1
fec0:0:0:ffff::2%1
fec0:0:0:ffff::3%1
NetBIOS over Tcpip. . . . . . . . : Enabled

Everything is correct, except that i dont know where its getting IPv6 anything, like those IPv6 DNS servers, no idea where those are coming from. They start with fec0 instead of fe80 so im not entirely sure if those are coming from the server or are local IP's (like the 169.254.x.x IP's) but it was definitely given an IPv6 IP address from what i would think is the server.

My DHCP scope is configured to be 192.168.16.10 to 192.168.16.200. My IPv4 server options in DHCP have my domain controller (which is the only server i have) setup with a router and DNS server, both as 192.168.16.2 (the IP configured in the LAN NIC). It also has DNS Domain Name setup as *.local (where * is my domain). My scope options are configured exactly the same.

I'm not really sure where else to look, but DNS IP's are not always being handed out. Sometimes they are, sometimes they arent. When they arent, server access seems to work but not internet, however, manually updating the adapter with 192.168.16.2 as the DNS address fixes it. This information is lost on a lot of other devices every time they are reconnected, so i need to find a solution for this.

Something that sometimes works is if i go to my LAN adapter on the DC and update the IPv4 gateway from 192.168.16.1, to 192.168.16.2, or make it blank (as long as it changes), sometimes everything seems to work perfectly for a day or so, sometimes not at all. Lately, not at all...

Any ideas what might be wrong? Anything i can do to test or find where the issue might be? The only thing i've found related to this on the internet is here in the forums where some guy found the issue was his NIC. I did have that issue myself, my onboard NIC just wouldnt work. I had my dual port NIC using only 1 port for WAN and the onboard for LAN and had a ton of problems, swapped them and continued to have problems, but when i put them both on the addon NIC, all those problems went away (although i didnt realize the DNS issue was present yet). I later added the VM's and gave them the onboard port, but they have been working perfectly fine. Could the onboard NIC cause this issue for all devices?

Answer 1

so how do i not multihome it?

One option is to install the hyper-v role (as only role) on host, Then stand up virtual machine guests for the various roles or applications. RRAS role should definitely be on its own instance of windows as a member server.

--please don't forget to Accept as answer if the reply is helpful--

Answer 2

• Multi-homing a domain controller will always cause no end to grief for active directory DNS.
• Do not install other roles on a hyper-v host. Add virtual machines for the various roles.
• Domain controller should be on it's own instance of windows, same for the RRAS / VPN server. Stand up additional virtual machines for other roles as needed.

--please don't forget to Accept as answer if the reply is helpful--

Answer 3

That's what everyone tells me to do, but prior to this, I had this setup and working flawlessly on a system setup with Windows Server 2016 Datacenter. Minus the Hyper-V servers, i used to do all of this on a single server, i had this going on Server 2008, 2012, 2012 r2, most recently on 2016, and now i have it running on 2019 with this one issue.

It seems crazy to take up all that space for multiple other VM's containing Windows Server 2019 just for RRAS, DNS, DHCP, and the other roles. This is a home server, i expect issues and have always had small issues every now and then. Typically a reboot fixes any issues that come up but sometimes windows update changes things and i have to make small changes here and there, and im fine with that.

Has anyone ever experienced this before? If you have, what have you done? I've had this setup for years, its only now causing issues.

Answer 4

Regardless it is unstable and causes the unexpected results you experience. If further assistance is needed you can start a case here with product support.
https://support.serviceshub.microsoft.com/supportforbusiness

--please don't forget to Accept as answer if the reply is helpful--

Answer 5

Hi ，

Server runs DHCP, DNS (cringing yet?), AD, Hyper-V, IIS (which i should probably remove since all web traffic is sent to the VM's and the Synology NAS), and RRAS.

Agree with Dave, we wouldn't put all of those role on a DC. DC, DNS, DHCP can be fine together, the rest of Hyper-V, IIS and RRAS should be in other VM. Multihomed DCs will cause numerous issues.

For your reference:

Multihomed DCs with DNS, RRAS, and/or PPPoE adapters

Best Regards,

Candy

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