Connecting to a Cable Router

My situation is I use a TP-Link Archer c7 v.2 with OpenWRT as a WLAN Access point, since the Vodafone Cable Router (Arris) constantly kicks everyone out.

Now since the Vodafone Router is regularly resetting and throwing my static IP list overboard and even the login gets reset to standard I would like to use my TP-Link as the DCHP Server since I made good experiences with that.

But I rarely ever touched the pieces of OpenWRT that I thought I feal confident changing, so I never touched the Luci Sections like "Switch" "Firewall" and "Interfaces" ( Interfaces i modified it for the AP Mode) and I feal expecially worried about the Firewall, since I dont understand a word in that section.

Now to just change the Vodafone Router to Bridge Mode makes me worried, since it gets Updated a lot and the Firewall settings on that Router might be very good...

Is there an option to set up the OpenWRT router with his own NAT behind an already existing NAT from that Arris Router? Or how should I set up the settings in the Switch, Interfaces and Firewall sections to be somewhat on the safe side.

I run Pi-Hole on a Pi3 also and want to have that as my custom DNS Server also...

I really cant find any good documentations or tutorials for the Firewall section, mostly they are for the console use, and that I understand even less...

I hope that I can find help here.

That cable modem is defective and needs to be replaced. It is only going to get worse. Though it may only be overheating. Make sure to set it up in the position shown in the manual (which is almost always standing on edge, not laying flat) and with good air flow away from any sources of heat.

Even when you own the cable modem you don't control its firmware, so it is good policy to consider it untrustworthy like the rest of the Internet. The default OpenWrt firewall is designed for that. It will block all attempts to hack in from outside. It only needs to be changed if you are setting up a VPN server, game server, or web server in your house that needs to allow certain connections from outside.

If you do buy a cable modem get one that is purely a modem not a gateway. These only operate in bridge mode so they are easier to set up, generally just plug in and connect to the WAN port of your router. OpenWrt will do the firewalling.

1 Like

In your described scenario,
Suggest that you configure the Vodafone to bridge mode.
The default settings on OpenWrt should be more than sufficient for general network security.

Depending on your network traffic, the Archer C7 it may or may not be up to the task.
The C7 runs on a single core processor after all.
I retired my C7 and running a DIR-882 now.

How am I gonfiguring the Switch and Interface Part to make that work? Since I tried that once and didnt manage... So far in interfaces I only have the LAN to get an IP Adress to be used as AP. Our Household doesnt really has alot of traffic, maybe 2 streams of HD Video and youtube and a download, that should be about the max traffic I can imagine, so I guess that wont be the problem, when the kids grow older, maybe then a new Router since the Archer C7 is well aged now (but was well worth the money).

The Modem should not overheat at all, since its in the groundfloor where its a bit colder and its wall mounted, with the Arris design that makes a distance to the wall with about 3-4 cm.

Thank you very much for the help so far.

Use a default configuration, enable WiFi APs (on both bands if you want), plug the router WAN port into the modem, and you have a basic home network. This will work whether or not the modem is bridged.

The only complication is it will not work if the modem is not bridged and the modem is issuing IP addresses in the 192.168.1.X range, which conflict with OpenWrt's default LAN. In that case you will need to change OpenWrt LAN to a different range such as

1 Like

One question for my general understanding of OpenWRT maybe helpful for me, why do all the ISP Routers get updated sometimes twice a week and OpenWRT only updates every few months?

I mean I am happy my Archer gets updates at all since it has about 7 years now, so its for general understanding not a type of criticism

What ISP updates their routers twice a week!?!?

(And BTW, there's a new version of OpenWrt everyday.)

Majority of the ISP do not update that frequently.

"Stable Release builds" does not require weekly updates, since those releases rarely encounter security issues/bugs requiring immediate attention.