What router with DOCSIS modem for OpenWrt

As far as I can tell there is no open DOCSIS router or modem, that one can install OpenWrt on. your best/only bet is to configure a non-OpenWrt DOCSIS-modem-router into bridge-mode. This might even be possible with VirginMedia's default router or not I have no idea.

The way DOCSIS works, you will need to give the ISP essentially root control over the DOCSIS modem anyway, so IMHO it would not be terribly attractive to install OpenWrt directly on such a device, but that is clearly just my subjective opinion.


DOCSIS on boot does a handshake with the CMTS and downloads the provider firmware on boot.

There's no option for building your own modem unless you have deep pockets and use older standards that don't provide todays speed options. Also, the "modem" needs to be on the ISP whitelist to even get provisioned for service.

Modems are bridge devices unless you opt for the 2-in-1 setup with a built in router/wifi in the same box and you can't easily modify the FW to get those to do whatever you're trying to do.


Pretty sure all Virgin Media hubs can be put into a modem-only 'bridge' mode. The superhub 3 and 4 certainly can be.

Once the hub is in modem mode it'll connect to the VM network and then pass the public IP to whichever device is connected to the first LAN port. So just connect the WAN port of your openwrt router to that.

Although if you're planning to go any faster than about 100mbit you'll need to replace the HH5a as your router, it's not powerful enough to cope with the higher speeds.


Well all of this happens over the DOCSIS newtwork so in theory all of the expected responses could be spoofed, but I think there is simply nobody that went this route recently, but see https://media.ccc.de/v/32c3-7133-beyond_your_cable_modem#t=0 That is the ISP needs to believe the modem is in his allow-list, independent of whether that is a true statement or not.

I tend to see this differently. Pure modems ceased to exist a long time ago, nowadays these are all routers, just some of them can be configure to pretend to be a simple media-converter... (If you look at the dance a modem does with the CMTS it seems clear why manufacturers opt for full OSs instead of trying to hardcode all of this in ASICs, no?).

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Good that I can use my existing Hub for the time being especially if it works flawlessly for all this time and no vendor firmware can give me this many features.

DOCSIS is powerful for downloads speeds but I need 300Mbit download speed package to beat the FTTC 80/20Mbit upload speed.

It would be good to test this 300Mbit connection between DOCSIS modem/router/bridge device and OpenWRT device but first I need to get something from a higher shelf.

DOCSIS devices fall into different categories and depend more on the consumer to make the correct choice for their application.

I use a MB8600 and it's a pure bridge from DOCSIS to Ethernet. The only thing to be configured from the admin page of the modem is whether to bundle the 4 gig ports on the back into a LACP or not. There are some additional tweaks you can make to fine tune the signals but, there's no routing being done at all.

We are talking past each other, I was referring to old-school "modems" of days of yore:
V92. 56K analog modems
ISDN adapters
that do not run full stack operating systems inside.... Given the complexities of DOCSIS provisioning (which even a "dumb" modem will need to handle) Even a device buttoned down to only offer bridged modem mode, will likely have the capabilities to act as a full router. But that is not to say that all DOCSIS Modems can be configured from the end-user side to act as full routers... I guess we are in agreement on some level?

Yes, there are differences in the old school POTS modems that truly only did 1/0's across copper.

Cable / DOCSIS though requires a bit more smarts to make things work. There are different levels though from a "modem" to a "gateway". The latter being a router / modem combined providing both the termination of the Coax and LAN capabilities.

For instance - https://pickmymodem.com/approved-modems-for-xfinity-internet-service/

You get into these hybrid options that include WIFI as a "gateway" all in one boxes. They sometimes provide an advantage to keeping everything contained into a single device such as the provider based modem/gateways do. From a technical standpoint though it complicates things if either side has an issue for repair / replacement.

And my point is, by necessity all DOCSIS 3.1 "modems" would be capable of acting a DOCSIS modem-router as well, not barring configurations by the manufacturer only exposing/implementing parts of that capability to the end-user... Where I am aiming at, modem, router, WiFI router are more market segmentation options than limitations by the SoC... (this can yield interesting blossoms, where a supposedly WiFi-less "DSL-router" when flashed with a firmware form the OEMs full-featured model magically gained 2.4 GHz, WiFi..., yes that is not DOCSIS, but it is the same level of "market segmentation" as seen in all consumer access devices).

To an extent I can see a possibility but, with volatile storage on reboot is why they download the configuration each time from the CMTS.

If something changes to make things more persistent then a shift to enabling more features via software/firmware could be an option.

The HW is segmented for 2 functions when moving from modem to gateway. The DOCSIS side still being "dumb" and downloading like a thin client and the router/AP side storing its configuration with persistent RAM.

To get there though things would need to be more modular in being able to add the radios for WIFI or ASICS for better switching.

Would you recommend a reliable/decent device that can handle 362Mbit down and 36Mbit upload on the WAN port? I think this is what I would go for.

Pretty much any router should be able to handle those speeds.

Personally I avoid things I can pick up in store somewhere as they're usually junk over the long term.

The bigger questions are budget and LAN Speeds that you want to see.

I can safely say that AX is preferred for performance after being on it for a year+ at this point. Not even for the highest speeds possible but more for how the new protocol handles the traffic of multiple devices.

For WAN wired only traffic you can make do with a $50 device. If you want something combining WAN + WIFI that's where the thievery comes into play.

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I understand you recommend to use

  1. a cheaper router (OpenWRT)
  2. a cheaper wireless AP (OpenWRT)
  3. potentially introduce a gigabit switch in between
    I had this in the past but WiFi AP I had could only do up to G so I switched to the Hub with N.

It really depend what you actually want to be able to do at 360/36 Mbps. What you could do is to get a wired only router like a raspberry pi4b with ethernet dongle or a nano pi 4rs or one of the rockchip-based alternatives, which should allow to do advanced processing like adblocking or traffic shaping at your link speed. And just re-use your old HH5A as dumb AP, accepting that on the WiFi side it will unlikely be able to sustain the ~360 Mbps your WAN link maximally allows. The beauty of such a set-up is that you can easy replace the AP or add additional APs for beter WiFi coverage without having to interrupt your internet access.

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Yes, it makes sense, great that you mentioned about Raspberry Pi because I have a number of them beginning from Raspberry Pi 1 B+. I will definitely utilize one them for that purpose. I think this can also be done with Pi 3 B+ (I saw someone mentioned that Gigabit Ethernet port on Pi 3 B+ can only do 300Mbit).
Do you know a reliable Gigabit Ethernet dongle for that?

Frankly I don't need a killer WiFi and I tend to use a wire where I can. It can be capped at 100Mbit.

With prices of PI so low it's worthwhile to use the latest version 4 and build on top of that.

AP's - I use a NWA210AX @ $160 but, you could probably get away with the NWA110AX for $130 due to the reduced needs. They cover 1000+ sq ft nicely and when you're close to them I can hit 1.5gbps to my internal network for moving files and such using AX210 Intel adapters.

For a wired dongle just abut any should work fine and they're dirt cheap. I use a 5GE one for when I really need LAN speed and that ran me $70.

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Not sure it will work with the Pi3's but the TP-Link UE300 seems to be one were a number of folks report success with. But not everybody seems happy with USB ethernet. And there are better ARM based boards around to base a router on. What the pi's have going for them is their relative large number and so far decent track record at fixing bugs and developing new versions while keeping older ones still available.

In which case I would start with your existing HH5A configured as dumb AP.

If however you want newer WiFi and OpenWrt, I believe this thread might be interesting: Belkin RT3200/Linksys E8450 WiFi AX discussion

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The RPi3 should not be considered for these tasks, it still builds around USB2 as its main system bus on a USB2 hub connecting onboard and external USB ethernet cards, as a result I/O performance is bad™.

Only the RPi4 finally improves this situation and can be used as a fast (wired-only) router.

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I'm on the VM 500mbit service (previously on 350). Use a RPi4 with UE300 ethernet dongle for WAN. LAN is connected through a gigabit switch. Wireless is sorted by a TP-Link EAP245 (don't have any AX devices so happy with this for time being). Setup has been absolutely rock solid for coming up on 2 years now.

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