DHCP & DNS from ISP?

Hi, guys!

I just bought a Tenda AC6. I want to run my own DHCP and DNS servers, so I bought this to have a LAN in and the ability to get at the settings myself (ISP only says “we run DHCP and DNS”, I want to run PiHole).

When I try to run the router downstream from all the switches, it doesn’t detect them. I suspect that once I plug in the WAN ethernet cable (which goes through 2 switches which go to 5 other machines), it ignores everything upstream from it, not handing out IP addresses into the WAN connection?

How can I fix it? I could buy a small mikrotik to take care of DHCP and shit, but it’d be suboptimal. Should I do it that way?

I’m not sure I understand exactly what you are asking. Apologies.

The AC6 looks to be an all-in-one router with wifi, it’s WAN port should plug into your modem, and it should assign an IP address to anything that connects to it’s wifi or LAN ports.

You may need to configure your modem to be in bridging mode, and you might need to configure the AC6 for your ISP, and maybe clone the mac of the modem. For me to do similar I also have to obtain my credentials from my ISP and put those into the router behind the bridged modem.

The ISP DHCP should only be to your modem (and not the NAT’ed local network behind it or the AC6). The ISP provided modem will have preset DNS values, but you should be able to specifiy whichever DNS servers you want (OpenDNS or Google) in the AC6.

Alternatively you could double NAT the AC6 behind your ISP modem, it will work but is sub optimal for all sorts of networking reasons I don’t fully understand (latency being one of them).

You got me curious on Pi-Hole, Scott Helm (security dude) has written some blogs about his Ubiquiti and pi-hole setup. Really interesting:

https://scotthelme.co.uk/securing-dns-across-all-of-my-devices-with-pihole-dns-over-https-1-1-1-1/

Hi,

thanks for the answer, I have found the answer on my own.

My previous setup was (I got it by air with an antenna, so that’s where the connection to ISP comes from):

Antenna - switch - switch - Tenda AC6

Which caused trouble, because when I had my LAN cable from the switch connected to the WAN port, the Tenda just thought there is nothing upstream from it. That is why it refused to hand out DHCP leases on the WAN port.

I solved the issue (when I needed the tenda in a central location and didn’t want a recabling job) by putting a small, shitty TP-link router between the antenna and the first switch. This router takes care of DHCP, I can set my DNS there and everything’s fine.

Now the network is:

Antenna - TPLINK - switch - switch - Tenda (in AP mode)

It solved my issue, although I got an idea for an improvement of this setup, since the router I have is wireless as well (which I turned off), but I have 2 boxes where I could’ve had just the switch. I heard about “layer 3 switches”, could they take care of some of my issues?

Also, the PiHole DNS setup is awesome! It takes care of all the devices’ ads, there are boatloads of adblocking lists on github, so for a while, I even blocked Windows telemetry (although, that one showed my windows computers as “not accessible to the internet”, the small triangle near the connection icon). Other than that, I can only recommend it!

Layer 3 (which is IP) switch is actually a router. Layer 2 (which is Ethernet) switch is actually a bridge.

The part that will blow your mind is that your ‘antenna’ is a probably a router and firewall too.

I understand your OP better now. Yes a router will only expect to either be assigned an IP on its WAN port or have a static one set for it. It won’t look to assign out networks. The firewall will also shield whatever is on the LAN againsts incoming traffic from the WAN port, so I can see why things were not working for you.

Not so much “blow your mind” as “make me rage” because I don’t own it, the antenna belongs to the ISP. If I had access to it, I would’ve used that and had no issue.

Plus, I just found out there’s OpenWRT for my TL-WR740N (don’t know the device model right now). I’ll install that ASAP, it’s the one I’m running as my router for DHCP.

Will there be any issues if I have:

30Mb/s connection from ISP
100Mb/s connection from antenna to router and from router to GLAN switch
GLAN in the house
Will the old TP-link router somehow throttle my in-house connection?

Thanks for the answer, though! Know some good L3 switches? From amazon, I don’t really know what to pick, I’m new to the specs of (what I searched for as) wifi-less routers.

Well, I got them to work, will be running OpenWRT on it soon! :slight_smile:

Mostly. They’re a cut-down high speed router (the only link layer protocol they do is ethernet), but yeah essentially true.

A traditional “router” can do protocols other than ethernet; because a layer 3 switch doesn’t have to deal with any of that (re-encapsulating into different media) it can be optimised for much higher speed routing.

Many layer 3 switches do not support NAT for example.

Well damn. Is there such a thing as a “wifi-less” router? All I see is wifi this, 802.11ac that…

I WANT A ROUTER WITH ONLY PORTS HANGING OFF IT.

Is there such a thing sub-40$? I only see these rackmounts that are 64 ports and have everything but the kitchen sink for 250$, I don’t need that.

I’m sure Draytek, Ubiquiti and Mikrotik all make routers that are just routers, no wifi and no modem included (just a WAN port). I doubt you’ll get one for under $40 though.

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The EdgeRouter-X can be had for $50, and it works great for what it is. That’s if you can afford $10 more.

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