Help Ubuntu Server 22.04.2 Active Directory Domain Controller

I must be honest I am officially stumped and seek the help of the Ubuntu geniuses. I am pretty new to linux in general with a few years of very basic tinkering before this project. As a result I have been using the following guide (among many others before this) to help me setup a domain controller for my network:

Samba Based Active Directory on Ubuntu 22.04

I followed the steps pretty much to the letter obviously changing the FQDN, IP addresses etc to match my setup. All settings apply with no issues/errors. The controller has been provisioned, enabled and a status check states its active and running.

I get as far as checking the controller by running:

host -t A cserv.lan 

This is where the wheels come off where the output I receive is:

;; communications error to 10.0.2.15#53: connection refused
;; communications error to 10.0.2.15#53: connection refused
Host cserv.lan not found: 3(NXDOMAIN)

I've tried re-provisioning the controller, editing the hosts file, smd.conf from solutions found from literally hours of searching possible fixes online. I've gone so far as to try different guides (at least 5 which all are pretty similar in steps) and still get to the same issue. I'm definitely doing something wrong each time.

My goal is to have an Active Directory Domain Controller to authenticate a few users on a few windows machines running win 10 pro on the cserv.lan domain. Similar to using a Win server AD DC setup. I'm currently testing the setup on a VM which I suspect is partly the issue. Upon getting the config down I plan to deploy this locally on another server and not through a VM.

Im using Vitual Box which is providing a NAT network to my 2 test VM's that they operate on the same network; the ubuntu DC and a win 10 pro VM. I get a steady ping from to the windows machine to the server when pinging the DC's IP address.

I'm using the following settings for the server if this helps:

Netbios/server name: ash-dc
FQDN: ash-dc.cserv.lan
domain: cserv.lan
Server IP: 10.0.2.15 (provided by virtual box)
DNS forwarder: 8.8.8.8 (also tried VM gateway 10.0.2.2)
DNS Backend: SAMBA_INTERNAL
Server Role: DC

The /etc/hosts file contents:

127.0.0.1 localhost (also tried 127.0.0.1 ash-dc.cserv.lan ash-dc)
127.0.1.1 ash-dc
10.0.2.15 ash-dc.cserv.lan ash-dc

# The following lines are desirable for IPv6 compatible hosts
::1      ip6-localhost ip6-loopback
fe00::0  ip6-localnet
ff00::0  ip6-mcastprefix
ff02::1  ip6-allnodes
ff02::2  ip6-allrouters

resolv.conf

# Samba server IP address
nameserver 10.0.2.15

# fallback resolver
nameserver 8.8.8.8

# main domain for samba
search cserv.lan

smb.conf

# Global parameters
[global]
    dns forwarder = 8.8.8.8
    netbios name = ASH-DC
    realm = CSERV.LAN
    server role = active directory domain controller
    workgroup = CSERV

[sysvol]
    path = /var/lib/samba/sysvol
    read only = No

[netlogon]
    path = /var/lib/samba/sysvol/cserv.lan/scripts
    read only = No

krb5.conf

[libdefaults]
    default_realm = CSERV.LAN
    dns_lookup_realm = false
    dns_lookup_kdc = true

[realms]
CSERV.LAN = {
    default_domain = cserv.lan
}

[domain_realm]
    ash-dc = CSERV.LAN

Please any assistance in this regard will be greatly appreciated. If the guide I'm following is flawed could you perhaps point me in the direction on one that works? Thank you in advance for taking the time guys.