Router died, modem + pihole = slow?


Aha that bit confused me … dont ever mention that r6400 router again !!!
RIP in silicon heaven :wink:

Have you tried reverting back to before without Pi-hole when you didnt had “massive lag spokes” and do the below:

See if “massive lag spokes” occur again ?
And just to be sure, what upstream DNS server(s) have you selected/configured in Pi-hole ?


I think youre referring to statically settings a DNS for each mahine? That is (for my network) assign it to and allow the modem to stay as default? I can give that a shot if I understand correctly.

I have cloudflare set as my DNS. Always have, I think I may try setting my dns to that via my modem and let that go for a bit to see if that causes lag before I bring the pi back into the world =).

And yeah I know “massive lag spOkes” sounds crazy but when I played games my latency would go from 50-80 to 1k+ for a minute then come back down. The pi would take 5+ minutes to update, websites would load 1/2 way then pause for a bit… etc etc etc.

But back to my origional question deHakkelaar - is there any debug command on the pi to run to see whats going on and if theres any retires? To me it makes sense with the webpages and could lead to the correct resolution via rabbit holes.


For diagnosing first, apply on the client thats troubled the most.

Nothing wrong selecting different upstream for diagnosing.

Bit hard as not sure yet whats going on but there is always the Pi-hole logs:

pihole -t


I knew about pihole -t… Doesnt show me much to whats going on. I also checked out dmesg to see if its a sdcard issue with no useful information.


Moved the modem to as primary dns, secondary dns is also cf at So far no issues. I think I have got to the point where its narrowed down to the pi.



Looks like in your modem should reserve an IP address for your rpi. Generally I would always reserve over statically assigning it on the device. Here is how I did that on the xfinity gateway.

So now, assuming your starting fresh with a fresh install Rasbian, go ahead and install pihole. After that you just assign the dns to your devices. There are a couple ways to do that found here

You will start to run into problems acquiring the DNS server if you do not flush you devices DHCP cache properly. In windows I disable and turn back on the adapter in the adapter options for the network. But for any device just rebooting will give you the new DNS. Keep in mind there’s nothing wrong with using your modems DHCP server. Unless there are features on the pihole DHCP you need, stick with your modems defaults!

After you get that running you can still use cloudflare’s DNS before cascading to the pihole DNS.


Yup. Done all this. The issue is something within the pi…


I’m going to post another debug token when I get home. These suggestions really aren’t doing anything unfortunately. Hopefully we can get this resolved.


Under your LAN and IP settings, you have defined the Pi-hole IP ( as your sole DNS ?

Try disabling thr DNS cache:


Is your gateway using IPV6 DNS servers? If yes, try disabling the IPV6 on the wan side or set the IPV6 IP of the Pi-hole under ipv6 WAN dns:

this should not happen. The DHCP lease request should be answered regardless of incoming connection type by the Pi-hole.

If the router does not broadcast the requests originating from the WiFi clients then the issue is isolated to the Router.

Try setting the Pi-hole IP under WAN IP address / Select DNS type.

If you run this on a client and the IP resolves, your DNS request DID go through and it DID resolve properly.

So if you can “translate” a name into an IP , the DNS server (Pi-hole in this case) did the job.

If you CAN’T access pages, then the routing is messed up.

Where does it fail with a tracert/traceroute?


Did everything except DNS cache, theres no option for it on my modem.

Redid dhcp, I cant even pull an IP, yes this point to modem issue. As soon as I statically set an IP I have good connectivity but the net is slow, nslookup is showing pihole as DNS. Traceroute comes back super slow.

I gave DHCP back to the modem, started an update on the lists I have for my pi at 19:43, its 19:55 and its still not done. Actually just finished at :56, All retrievals successful minus one.

The pi blocking is running extremely slow. I am now at 1.5m blocklist and after about 5 minutes of decent browsing (as I am writing my girlfriend is on her phone doing pinterest, I am taking breaks too googling around) 3, yes three, queries are blocked and yes were both on wifi via the modem.

I am not sure what else to do at this point to be honest.


Here is something I noticed:
Pi-hole Ethernet Interface:|wlan0|
Pi-hole IPv4 address:||
Pi-hole IPv6 address:||
Pi-hole hostname:pi

That is from the GUI, why does it think the ip is on wlan0 (wireless) when:
~ $ ifconfig
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500

and… wlan0 is down? (intentionally)


What if you pihole -r > Reconfigure and choose eth0 instead of wlan0?


Alright I ran pihole -r, re added my blocked sources. Ill let it run for a while and report back.


A couple more minutes of browsing and a total of 5 blocked domains this time… Yeah somethings up. I notice all the IPs are also coming from instead of their assigned ips.

The cable company is sending me a new modem. I am going to put that in and configure it and we will go from there seeing as nobody here even wants to start looking at my pi.


Maybe I missed it but how are you configuring your devices to use Pi-hole?


I have done it via static dns on the device itself and forced it through the modem (done it together so both the device and modem have it, I have also done it where just the modem has it and just where the device has it).

After browsing the net some more on pinterest, ebaums world and just random sites to try and get ads for like 20 more minutes and let the net just be overnight, it went up a total of about 20 blocks. Before the router died I was in the ~60% blocking range and now I am less than 10 with roughly the same amount of DNS’s on my blocklist.

I believe everybody says its my modem, I agree it most likely is. Just want to figure out why and that may be too off topic for this forum. On the main page of the modem it says the DNS is statically set to .30, the dynamic is grayed out. Its possible they have some override code in the background I just wont see. I got an update and I am getting a 2200 instead of a 3200 today. If I get that setup Ill update later unless somebody chimes in with a question.


Thats because I dont suspect anything wrong with Pi as you told us before switching modem/router, you didnt experience any issues.

When the new router arrives, can you post screenshots of all settings related to DNS and DHCP ?
Lets turn you into a Pi-hole expert and try set it up the proper way.
The proper way, if possible with available router settings, is to have the routers DHCP service hand out Pi-hole’s IP address as the only DNS server to the clients:

C:\>ipconfig /all

Windows IP Configuration

Ethernet adapter Local Area Connection:

   DHCP Enabled. . . . . . . . . . . : Yes
   Autoconfiguration Enabled . . . . : Yes
   IPv4 Address. . . . . . . . . . . :
   Subnet Mask . . . . . . . . . . . :
   Lease Obtained. . . . . . . . . . : woensdag 27 juni 2018 17:14:56
   Lease Expires . . . . . . . . . . : donderdag 28 juni 2018 17:14:56
   Default Gateway . . . . . . . . . :
   DHCP Server . . . . . . . . . . . :
   DNS Servers . . . . . . . . . . . :

If router DHCP server settings lacking/missing, you can switch off the DHCP service on the router and activate Pi-hole’s DHCP service as a replacement.

As a very last resort and not a desired solution, you can configure the router to use Pi-hole as upstream DNS resolver (usually called WAN DNS or something).
But with that last one, you miss out on nice client statistics as all the DNS requests are coming from the router instead of the clients (from Pi-hole’s perspective).

If things still laggy, we can dig a bit deeper.


Alright. Ill be looking into it today.

But yes, dont take any of this without thinking I appreciate the help. I do, and trust me I am far from an expert. I am always willing to learn.


Alright something strange happened while I was at work yesterday.

First off the modem has not arrived yet. So I havent touched anything BUT… I noticed all the ips the day before yesterday were coming from .1, the modem. I get home last night and start looking through things and see they are now all coming from .10-.29, which is what I have blocked off for my home network and theres no more slowdowns that I noticed. I think Ill keep things running the way they are now and after a little bit switch the dhcp over to the pi.

The block rate has risen a little bit, from <10% to about 30% now which is better, but not as great as when it was around 60%.

The only explanation I have for this is that maybe there is a cache inside the modem that cannot be cleared? I have no idea its strange.


30% blocked sounds healthy and is exactly the same as on my Pi.

Keep in mind that DHCP client leases have a lease duration similar as the TTL (Time To Live) on DNS records.
You can see when a client got its lease, from whom it got the lease, and when it expires with the ipconfig /all command run on the game rig (I presume its Windows).

If want to stick with the current router/modem, you could post screenshots of current DNS & DHCP settings on the router for us to have a look ?