Unable to access router after pihole DHCP activated (ASUS router)

Help
1

Expected Behaviour: Pihole to act as DHCP and still be able to access router gui via ip or name.
Asus AC68U
Pi3 B+

Actual Behaviour:
Everything works great until turning off DHCP on router and turning on DHCP on pihole. Network still functions but ipscan of router shows no ports open. Router is still functioning. Trying to connect via ip using a browser gives "[IP] refused to connect"
I have smashed the search function and have found similar issues but none have helped.

I have set router.asus.com as the correct IP in the local DNS records.
tracert shows a single hop to router when using both router.asus.com and IP.
nslookup hits pihole then router when using both router.asus.com and IP. .

Debug Token:https://tricorder.pi-hole.net/0fb58ixseh

2

Commonly, a router configures a static IP for itself, so it would never request a DHCP lease.
Without DHCP registration through Pi-hole's DHCP server, Pi-hole also remains unaware of any names your router may use for itself.

You can create the missing Local DNS Records via Pi-hole's UI.

3

Thanks @Bucking_Horn but as I mentioned in my first post this has already been done. My DHCP also starts a number after the router so i know its not assigning that IP anywhere else. Even if I had not set it up in the Local DNS Records, access to my router using the static IP should work right?

4

You are using a public IP network:

*** [ DIAGNOSING ]: Discovering active DHCP servers (takes 10 seconds)
   Scanning all your interfaces for DHCP servers
   Timeout: 10 seconds
   
   * Received 300 bytes from eth0:142.x.x.45
     Offered IP address: 142.x.x.46
     Server IP address: 142.x.x.45
     Relay-agent IP address: N/A
     BOOTP server: (empty)
     BOOTP file: (empty)
     DHCP options:
      Message type: DHCPOFFER (2)
      server-identifier: 142.x.x.45
      lease-time: 604800 ( 7d )
      renewal-time: 302400 ( 3d 12h )
      rebinding-time: 529200 ( 6d 3h )
      netmask: 255.255.255.0
      broadcast: 142.x.x.255
      dns-server: 142.x.x.45
      domain-name: "lan"
      router: 142.x.x.1
      --- end of options ---
    
   DHCP packets received on interface eth0: 1
   DHCP packets received on interface lo: 0

You should use private address ranges with Pi-hole.

Using public IPs may turn your Pi-hole into an open resolver, which poses a potential threat for all Internet users, e.g. by serving as a multiplier in a DNS Amplification attack.

The Pi-hole team strongly discourages Pi-hole’s usage as an open resolver , and we won't provide support in that case.

5

I was not actually aware of that. Ill change my IP range and see if that changes anything. Will report back tonight. Thanks for the help.

6

So after all that it seems there may be something wrong with the Asus AC68U. After a few reboots during setup my router closes port 80 used for the httpd and refuses to reopen it. I cant figure out why. Managed to get my router setup correct without it closing so for the time being its all up and running! It took a dozen attempts but PiHole was nothing to do with it.

Thanks for the help :slight_smile:

7

I switched to ASUS XT8 router recently and just like to give my solution (the FW looks quite similar so it should be similar) I did like this:

In ASUS router:

  • Changed router IP to 192.168.0.1 (as I have MySQL and MariaDB instances using 192.168.0.x)
  • Disabled router DHCP
  • Assigned Pi-Hole IP (Note: Static IP!) as DNS server (in my case 192.168.0.252)

In Pi-Hole:

  • Added router IP (192.168.0.1)
  • Configured DHCP scope (in my case 192.168.0.100 - 200.
  • Configured static leases (Servers, MySQL and MariaDB's, ...)
  • Selected upstream DNS servers

Restart of router & Pi-Hole.
Some boxes required force of DHCP IP renewal but after that it works flawlessly!

8

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