Low DSL DL and UL speed(BT homehub 5A)-Deutsch telekom

Yes, looks like the DLM system raised the maximum allowed sync from 63.680*/32 Mbps to 70/37 Mbps....
Looking at the SNR margin it looks like there is some more increases possible for the download direction, the upload might have reached the maximum DLM is willing to allow, but let's see how this develops over time....

) 63.680 is one of the two the profiles* max for VDSL50, so my best guess is that DLM is configured to never noticeably drop below the upper sync limit of the lower speed tarifs, but that really is pure speculation.
**) For completeness for VDSL2-vectoring enabled links (so by now essentially all) these are: 63.680/12.736 or the VDSL100 max profile of 116.8/46.720 Mbps. No idea on which basis Telekom decides which to select. After enabling vectoring the initial approach seems to have been to use the VDSL100 profile limit (potentially to enable easy customer self-service plan increases to VDSL100, as the system would know the achievable synch speed already) but that apparently did not turn out as robust and reliable as initially hoped, so at least some links a running on the lower profile.

In case anybody should wonder these profile numbers are explicitly mentioned in reference contracts for bitstream access that Telekom publishes on their website and they seem to anecdotally match what I find reported "from the wild".

Hi Moeller0
there is no improvement after 1.5weeks. i get a fritzbox 7590AX router, i plan to use it to isolate what's the problem.

Why not a Draytek Modem?
new: Vigor 167 https://www.draytek.de/vigor167.html
used Vigor 165: https://www.draytek.de/vigor165.html
or used Vigor 130: https://www.draytek.de/vigor130.html

With a VDSL2 modem like this you are free to choose whatever OpenWrt wifi router with ethernet uplink you like. It's just configuring PPPoE on the router. VLAN tagging is done on the modem.

Give it more time... for me it took >> 14 days after removing the root cause....
Then again the DLM acts in mysterious ways, that is to say we do not know exactly which numbers it looks at and how it weighs them....

No opinion on draytek, but the mentioned 7950AX uses a broadcom dsl modem which is rumored to cooperate better with broadcom linecards... the downside, compared to lantiq, is that one can not install/run OpenWrt on those broadcom modem routers.

My experience with my Draytek modem is good. There are plenty of Draytek resources and experience to read about these DSL modems online and they have useful telephone support in the event it is needed. Even tweaking DSL settings is possible, and DSL line analysis.

I don't know which DSL chipset inside is used, it works, great speed for the old **** existing line installation to the DSLAM. I am satisfied.

My main benefit is that I can use whatever OpenWrt router I like by accepting two devices instead of just one. And I don't need to care for DSL details, the modem just works.

All of this fine and I am happy you found a great modem for your use-case. However for the OP a broadcom based modem/router might make sense right now. I have no idea whether any /which draytek device uses a broadcom chipset....

Thanks for the advise, i will wait for 14 or more days.

Why is this a must requirement when possible advantages are just a rumor?

I agree to you that single vendor modem and DSLAM combinations should be more compatible than different combinations. But it’s not a must have to switch to this based on rumors that might work better. What matters is only if the connection is fast, stable and low error rates. The vendor of the modem is more or less irrelevant if the user experience is good (enough).

Draytek Vigor modems provide different modem codes that offer different line characteristics depending on the individual line and DSLAM configuration. I see more opportunities in trying these than just switching to one different modem with one single modem code based on the idea that Broadcom might work better with Broadcom.

Some Draytek Vigors (e.g. Vigor 130, Vigor 2760, Vigor 165 ...) are Lantiq-based. You can use their firmware on OpenWrt-powered devices as well: https://xdarklight.github.io/lantiq-xdsl-firmware-info/ and https://github.com/xdarklight/lantiq-xdsl-firmware-info/issues/34 for a list.

I was running a Vigor firmware on my FRITZ!7520 for quite some time before replacing the VDSL line.

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Who spoke of a 'must'-type requirement? Just something i wanted the OP to know. Why only a rumor, because only broadcom and maybe lantiq/maxlinear know for sure and they are not talking...

I actually think they should not, if all sides just follow the respective standards, but it was anecdotally observed in the field (including on my own link where a broadcom zyxel performed better (higher sync, less error and error correction event per time) than a BT HomeHub5A (running OpenWrt).

Sure, nobody talked of a strict requirement.

I am not going to stop you ;), for the OP however I stick to my assessment the 7950AX is worth trying.

Personally, I switched from a lantiq xrx200 BT HomeHub5A (configured as bridged-modem under OpenWrt with subtly broken vectoring) to a ZyXEL VMG1312* -B30A based on the broadcom BCM63168 chip (operated as brdged-modem under ZyxelOS), switched back to the xrx200 after @janh fixed the xrx200's vectoring issues, and finally switched to a lantiq/maxlinear vrx518 Fritzbox 7520 (bridged-modem under OpenWrt). Personally I am most happy with OpwnWrt as OS for a dsl modem. But still the BCM63168 performed noticeably better than the xrx200 so testing a broadcom modem on Deutsche Telekom's broadcom linecards seems anecdotally reasonable.

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Yes, I know. The point is trying OEM firmware and different modems.

The 7590AX uses a MaxLinear VRX619 modem. Maybe you are confusing it with the Broadcom-based 7530AX?

I would strongly recommend against the Vigor 130. It uses the same VR9 modem as the Home Hub 5A, but all of the available DSL firmware versions ("modem codes") are horribly outdated. The version that Draytek recommends for DTAG (modem 7) doesn't even support G.INP. The least outdated variant for the Annex B model is modem 4, but from my eyperience it is still far from ideal.

It really looks like the only problem here is the limitation by the DLM system.

Edit: After taking another look, the downstream uncorrected retransmissions might be an actual issue. Unfortunately, they must have occured more than 24 hours before you took the screenshot (both the history and SNR minimum/maximum are kept for that duration).

just chipping my 2 cents on this target

  1. It's possible that's just the speed you're paying for so that's the speed it's capped at (sorry if that's not the case just saying)
  2. These modems are all getting pretty old and unless you got your bt hh5a brand new never before used it probably got used a lot before you bought it and in my experience the connecting capabilities of individual modems can vary quite a bit i.e the actual state your modem is in possibly matters with this chipset so it's possible it's not strictly the line or even chipset features limiting your speed but the actual wear and tear state it is in
  3. The newer vrx518 target (fritzbox 7530) is just overall better so probably worth migrating to but I agree that depending where you are it can be hard to find one below a couple of hundred dollars. Even with this target though speeds can vary just on the state of the device, I have two 7530 and one connects a bit faster than the other one (eg 112 mbit/s vs 113-144) so there's some variation there, in my experience the variation is greater with different hh5a's (eg one modem might connect at 103 and the other might connect at 106 or 109).

Which affordable and available VDSL2 modem do you recommend instead? What are the actual benefits for the users?

Thanks, yes, I was extrapolating, badly ....

The lack of upstream G.INP in Vigor 130 modem4 firmware results in higher latency due to interleaving. With modem7 DSL firmware, the actual downstream data rate is in some cases noticably lower than the attainable rate, despite the DSLAM being configured to allow a higher rate. This particular issue also affected other VR9 modems (including Fritzboxes), but it was fixed by newer DSL firmware. Unfortunately Draytek never released a newer version for their VR9-based modems.

Note that my recommendation is specifically against the Vigor 130 in combination with a DSL line operated by DTAG. It might well perform better in other networks (especially if G.INP is not used). Newer devices like the Vigor 165 also use more recent DSL firmware, so they should work much better in general.

Personally I would still try to avoid Draytek devices if possible (the configuration interface requiring reboots for everything is quite annoying, there is some weird/buggy behaviour in the command line interface, and there are hints that their DrayOS might contain Linux code in violation of GPL). But I understand that local availability of alternatives might be an issue.

Personally, I use a Fritzbox 7520 with OpenWrt. Unfortunately, the modem in some of these devices (which cannot be distinguished externally) requires an additional patch that appears unlikely to get accepted into OpenWrt.

A good choice for a modem that just works here in Germany would be a cheap used Speedport or Digitalisierungsbox that supports bridge mode. Depending on the particular model, these only offer limited diagnostic possibilities, though.

I used a cheap Fritz 7412 for a few years as simple bridge modem. I bought it used for maybe 10 Euros....

Still, the line felt more stable when I replaced it with a 7520.

I would not buy a new VDSL modem these days as there are so many available for cheap on the used market.

Mediatek/Econet xDSL chipset - some people have luck with them but the one I tried would look up solid after 4-6 weeks :frowning: and some others reported similar issues so I'd avoid.

Lantiq VRX500 & VRX200 xDSL chipsets respectively. Not a fan of the interface on the 130 I had but it was as reliable as the FB7490, DM200 and TD-W8980 I've also run. Sadly the 165s were never sold here (Aus).

Having a good run so far with a FB7530 running an OpenWrt snapshot from just before the 23.05 branch - 8+ weeks VDSL connection uptime with no SRA events logged thus far.

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For me the issue is easy to solve. If there is a DSL line speed issue which cannot be solved with OpenWrt firmware: switch back to a DSL modem that is supported by the ISP. Open a case at ISP customer support. Either they can fix it, or not. If not: lower speed contract, try different modems if the speed is near the target rate, or switch to a different ISP.

But: it may be fun to try to solve ISP customer support problems with OpenWrt and dive into low level DSL details. I am also not stopping this. :slight_smile:

Thank you for reporting this and glad to hear there are improvements by doing so. What were the benefits of exchanging the DSL modems in the end?

For me a DSL modem is not much more as it was 20 years ago, just with today's DSL standards. If the connection is stable, performance is good, low latency, low error rates: all things are fine. I would much more like FTTH, but thats a different discussion.

When I look at the ancient worse condition the physical line is I am still mesmerized what both the DSLAM and my modem get out of this line. No need to over optimize if speed, stability and latency are all good.

I don't mean what would be the user benefit of having up to date hardware and firmware. I agree into your points in this. I mean what the user benefit would be if you already get the line speed of the ISP contract, you have fast path working and everything is working with expected performance and in stability.

What is the user benefit of diving into low level DSL things if the line already just works to specification and contract speed?

In which way are these better than a different or older modem which already gets stable line speed with fast path, from a user's perspective?