Considering whether switching from ADSL to FTTC

My ISP (Italy's Wind Infostrada) plans to switch off ADSL sooner or later and is now offering me an FTTC (100M) connection at the same price conditions as my current ADSL (20M). I have till the end of the week to accept or decline their offer and I'd like to make an informed decision.

I'm a longtime Openwrt home user with a somewhat complex setup:

  • external ADSL 2+ modem (a basic modem/router used as modem only, pppoe WAN connection managed by the main Openwrt router)
  • three tp-link routers with the latest openwrt (main router, an AP/switch and a WDS repeater)
  • a raspberry-like ARM webserver with letsencrypt https and DDNS
  • many PCs (linux, mac and win)
  • Synology NAS
  • TV and mobile stuff

I'm quite satisfied with my current setup but I will be forced to switch sooner or later so I might consider doing it now. What I'm most concerned about is:

  • I really want to use a router of my own and be its admin
  • I want to use an open firmware with all of its benefits
  • I need my webserver to be online (a low traffic dokuwiki site)

I'd need a new modem and I can choose if getting a modem/router for free from my ISP (Zyxel VMG8825-B or Dlink DVA-5592) or buy one myself and chose one supported by Openwrt. So here's a few questions:

  • does Openwrt support FTTC modems via VDSL2?
  • can I just use their modem/router as a modem only and keep my setup as is?

Any hints? Thanks!

If you are able to get a modem that supports "bridged" or "transparent" mode, then that leads to the simplest configuration -- the modem passes the DHCP information and packets directly to the OpenWrt router.

ftp://ftp2.zyxel.com/VMG8825-B50B/user_guide/VMG8825-B50B_V1.0.pdf mentions "bridge mode", though you should check with your ISP to determine if they support bridge mode as well. I didn't check the other unit.

In my opinion, a separate modem is an advantage, especially in a world where the ISP controls the firmware of the modem. Should you have any problem with either the modem or your router, they can be rebooted, reconfigured, or replaced independently.

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As a matter of fact my current modem is a router in bridged mode, so that would be great. I'll check if that is a viable option and if the phone (not the mobile) will work in that case since it should be managed by the modem through dedicated ports.

You might also check if there's an IP passthrough mode, it's kind of a "bridge mode lite". Or a DMZ mode (where you get a private IP, but all the incoming ports are sent to you anyway). Those modes would be likely to support the phone, and still allow your incoming connections to be controlled by OpenWrt.

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FTTC means they will install a cabinet near your home that converts from fiber to VDSL. This is usually in the wiring closet of an apartment building. The final link to your modem will still be a copper wire pair.

After replacing the modem with one that is VDSL-capable and setting it in pppoe bridge mode, you should be able to continue to use the rest of your network exactly as before.

If your analog phone line is presently on the same wire pair as the ADSL signal (using a filter to keep DSL signals from being heard on the phone), you will need to change that. The new system is to send only data in/out on the wire pair, and encode phone calls into VOIP within the house to be sent out digitally. The modem contains a VOIP adapter that offers the analog phone service on a jack on the modem. You will need to change your wiring so that your phone(s) are fed from this jack instead of from the wires going into the house.

If you use their modem, the phone company will administer the VOIP service for you. You would only need to plug your phone(s) into the modem and keep power supplied to the modem.

FTTC is just marketing speech, for all intents and purposes you'll get VDSL2 (and probably with vectoring) - where the DSLAM is located doesn't really make a difference (aside from the expectable throughput). What you do need to confirm before switching, is your future phone situation, namely if it continues(?) to be analogue phones (with its frequencies just split off with a splitter or line filter) or VoIP/ SIP ("All-IP").

Yes, using a dedicated modem is usually a good idea. If your ISP's modems do support full bridge mode (including with their, potentially, ISP branded firmware), there's no reason not to use those - but there are also OpenWrt supported options, see https://openwrt.org/docs/techref/hardware/soc/soc.lantiq (VRX200/ VR9). Some of those (especially prior ISP branded ones) can be found very cheap on the used market, the Netgear DM200 (both with the vendor firmware or OpenWrt) would probably be the cheapest new option.

In terms of your routing situation you can probably keep your current router (assuming it isn't too low-end and your expectations in terms of SQM, VPN or other CPU intensive services), you probably only need to change your current configuration to include VLAN tagging on WAN. The BT HomeHub 5.0 Type A could be one of the few OpenWrt supported devices that include VDSL2 modem and wireless router (with good wlan cards). While those are rather cheap, doing the initial flashing is not for the faint of heart (read its wiki page and the https://openwrt.ebilan.co.uk/ forum before buying - or get a device preflashed with OpenWrt). While the BT HomeHub 5 Type A is a pretty nice device, it's a bit at its limit with 100 MBit/s WAN throughput (requires flow-offloading to be enabled, which isn't totally stable yet).

If your ISP requires switching to VoIP/ SIP, this will be the only slightly harder topic. Even if your ISP modem options include FXS (phone-) ports, those won't be usuable in bridge mode. Yes, there are also options with OpenWrt on lantiq devices with FXS ports, but asterisk and chan_lantiq is probably not what you're looking for (it works, but configuring that securely isn't really 'fun', furthermore you'd need a dedicated device just for that due to the afforementioned performance limits of the lantiq platform). A dedicated SIP-ATA (with or without DECT support) is probably an easier option here.

If your analog phone line is presently on the same wire pair as the ADSL signal (using a filter to keep DSL signals from being heard on the phone), you will need to change that.

That's what I've got now and analog phones should be adapted for VOIP. One of these is a (pulsed disc) phone is from the '70s :wink:


800px-Telefono_Siemens_Auso_S62
The other one is a DTMF cordless.

So, correct me if I'm wrong:

  • I can't use a new VDSL capable router in bridged mode or I'll lose analog phones
  • there are very few devices with VDSL support in Openwrt anyway
  • VOIP would be managed by my ISP so I'm stuck with their router or an adapter

Not what I whised for :frowning:

What now?

Pulse dialing should be the only obstacle here (yes, chan_lantiq can still do it, but most commercial SIP ATAs can't), but that can be solved with the cheapest sub-10 buck phone you can get.

Other than that you 'just' need an additional SIP ATA/ pbx - and configure it with your ISP's access credentials. Yes, this raises the bar to three different devcies - modem, router and SIP ATA (you can make that two with the BT Home Hub 5 Type A, by covering modem and router in one device - but the SIP ATA will need to be its own device).

May I suggest the Grandstream HT802 as pretty much the only ipv6 capable Analog Telephone Adapter. It works reasonably well in my experience.

Apart from that phone - that has my age and carries some emotional value - a BT router (Atheros WDS should work as well) flashed with Openwrt and an adapter for the DTMF phone would do?

Except from having an extra device, using a new router as a modem only - no Openwrt firmware - is a worse solution?

Shuld I consider a fritzbox device? The 7490 was offered till a couple of months ago instead of the two mentioned.

The (only) purpose of the BT router would be avoiding the modem alltogether, because it is a decent modem itself - if you go with an external modem, you can either keep your existing router or get a better (read faster, the lantiq VRX268 devices are marginal for 100 MBit/s, but they can do the job with flow-offloading enabled) one.

There are all-in-one devices, like the AVM Fritz!Box line, but those won't be able to run OpenWrt (you could run them as SIP ATA and DECT base station behind your OpenWrt router though; respectively the few that are supported by OpenWrt won't be able to achieve 100 MBit/s while also doing FXS with asterisk/ chan_lantiq under OpenWrt at the same time).

I would look into letting the ISP provide the modem and running your own nice router behind the modem. This also allows you to push back against the ISP when things don't work (hey it's your modem and when I connect my laptop up to it directly it doesn't work, etc). Ideally the ISP can put the modem in bridge mode and you run your routers behind the modem, less ideal is the IP Passthrough or DMZ type modes which would work fine. Worst case is double NAT which would break your ability to host your Wiki.

Worst case you put your wiki on a hosting service such as Linode or Digital Ocean for $5/mo and you can also add additional services there, and enjoy your substantially increased home network speeds.

The Grandstream HT802 has a little toggle to "enable pulse dialing" so your ancient phone is good to go!

@dlakelan
I would imagine that people these days use DECT solutions :wink:
Gigaset N510 IP Pro is a nice box that's usually very cheap (~70-120 EUR) and works well.

Just use the modem/gateway you get from your provider, if it supports bridge mode it's all fine and dandy otherwise you're most likely looking at Double NAT or no Internet at all as most DSL providers uses PPPoE doesn't necessarily provide you with auth information. As for the phones, ditch the old 70s phone and get a new DECT based one or grab something like the N510, That is if your VoIP provider supports enduser provided hardware.

Thank you all for answering!

I'll add some information:

  • my ISP is giving me a modem/router anyway and for free (D-link DVA5592 or Zyxel VMG8825-B50B)
  • I don't plan to buy new phones; I barely use it since every call goes through mobile these days

If I got it right I'd better use their router as a modem in bridge mode and keep my current setup. I'll lose the phone service this way so I'll have to buy an analogue phone adapter to get my cordless phone working.

I'll try if my old disc phone works through the adapter; if not I'll give up... or maybe build a pulse to tone converter (that project from hackaday would be nice).

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You might need to upgrade your router for the higher speeds. But no one should use the ISP router as a router, since it gives your ISP control over your personal network, so you should definitely keep your same structure even if you do need to upgrade components.