@DustinB3403 they're cheapo TP-Link routers acting as APs (they have an AP mode) I think they are sus because technically they are capable of DNS and DHCP themselves...could be one going rouge

UPDATE: We have replaced the router, wifi APs and enabled DHCP forwarding .... it hasn't gone down since! *Really don't want to Jinx it" Thanks all for you help I really appreciate it

UPDATE: We have replaced the router, wifi APs and enabled DHCP forwarding .... it hasn't gone down since! *Really don't want to Jinx it" Thanks all for you help I really appreciate it

@Dashrender @notverypunny Good ideas! Thanks!

@DustinB3403 they're cheapo TP-Link routers acting as APs (they have an AP mode) I think they are sus because technically they are capable of DNS and DHCP themselves...could be one going rouge

@Dashrender Draytek 2860 (being replaced this week) - 3 * unifi switches (fibre linked) and a few rando APs dotted around. It's quite a simple setup, the APs are a bit sus. I could pull them all out...

@Obsolesce yes, the only way I can connect to it is through the hosts Hyper-V and the shares on the AD server drop

@Obsolesce DNS logs show one interesting one linked, the log says that its transferred the master role from itself to itself https://imgur.com/a/4I75qnB if you mean somewhere else I apologise!

@Dashrender It happens for every device on the network!

@JasGot Yes the AD server does DNS and DHCP too, yes the Host on the domain

@notverypunny When I ping a known good IP i.e. 8.8.8.8 I get "...unreachable" rather than the "Ping request could not..."

@notverypunny said in Server 2019 randomly DNS stops:

DNS server / Domain Controller

No I inherited this unfortunately ! I'm sure we've all been here..

1. DHCP scope is configured with Router, DNS Servers (as the AD DNS ONLY) and DNS domain name of domain.co.uk - I mean it looks correct.
2. Clients get DNS from AD DNS server through DHCP as above and to my knowledge noone is capable of changing it on their desktops.
3. AD DNS server isn't set to loopback no, its set to its own IP (which is what I thought was properly configured)
4. Forwarders are set to Google and OpenDNS

I totally agree about the host reboot thing, its is in my opinion the most puzzling thing. Maybe I should retest that theory encase the times it hasn't worked is a fluke...the internet is a wireless link provided by a small ISP here in the UK and I'm not familiar with their service.

The whole thing is a huge headache. I've tried uninstalling my RMM tool encase that is the issue. I have noticed that when I teamviewer in sometimes that seems to either trigger it or I'm super (un)lucky...

@Obsolesce Lots of informational logs but not error or critical logs. I've looked through those and most of them say "I can't find x" because no DNS.

There are a lot of informational logs for directory sync but I'm not able to spot any specific events that look like a trigger.

Thank you for the info, much appreciated. It just went again and I tried this with no joy. w32time service was not running this time.

I tried running this again as well but it didn't help either..

nltest.exe /dsregdns

This is the wording of the Ping response. I did a net start/stop on dns too

Ping request could not find host bbc.co.uk. Please check the name and try again.

Went for a host reboot in the end.

DNS stops working randomly although the services continue to run. Cannot ping any external hosts.

First began last November, sometimes it happens multiple times per day sometimes it only happens once a week.

One Server 2019 (standard 1809) host with two vms, one AD, DNS, DHCP and file shares the other is an RDP server. A reboot of the host always gets it working again, a reboot of the AD vm doesn't (which I think is odd).

NTP time is out by -00.0016250ms and seems to be stable.
I do see this in my RMM when it goes and then opens when it comes back.

Monitor: Port Closed
Port closed.PortNo : '53', Protocol : 'TCP', ServiceName : 'DNS(dns.exe)

It happened just now and I ran

nltest.exe /dsregdns

As I had a load of NETLOGON errors in event viewer and it said to run that. It then started working again (this is the first time I've run that and first time I got it working again without a reboot).

I also have an inkling that it is when the w32time services runs as that does sometimes appear to be running when it goes.

Any ideas or experience with something like this shared would be much appreciated.