topic Re: Modem random drop-outs in Broadband

Modem random drop-outs

mdubash — Wed, 04 Dec 2024 12:40:21 GMT

Connection: FTTC VDSL 2

Router: Asus RT-AX58U with OpenWRT - standard set up, nothing special.

Modem: Huawei HG612 with latest Kitz forum reflashed firmware

Discussion: System, which is recent install, works fine most of the time, I'm getting full throughput compared to my old FritzBox, which worked for years but showed signs of giving up, hence the new hardware. DSLStats reports no problems. This problem manifested itself from the beginning of the new hardware's installation.

Problem: Randomly, the link between modem and router seems to fail, for just ten seconds or so while the router re-authenticates. It looks like a problem with the line card as authentication takes a fairly short time, while retraining takes much longer - and it's not doing that.

Fixes tried - all made no difference:

New router
Replacing the Ethernet cable
Re-orienting the modem to allow for better heat dissipation

Suggestions welcome, please!

Re: Modem random drop-outs

Townman — Wed, 04 Dec 2024 12:55:59 GMT

In the absence of helpful router stats, given that you have seen similar with different kit - consider REIN n SHINE. See Kitz.

Re: Modem random drop-outs

MisterW — Wed, 04 Dec 2024 13:55:18 GMT

@mdubash

Randomly, the link between modem and router seems to fail, for just ten seconds or so while the router re-authenticates. It looks like a problem with the line card as authentication takes a fairly short time, while retraining takes much longer - and it's not doing that.

Are you absolutely sure the modem isnt retraining ?

If you are, then check the openwrt kernel log for the WAN ethernet port (eth<n>) status. You may see something like

[9086704.622979] mtk_soc_eth 1e100000.ethernet eth0: Link is Down
[9086717.102934] mtk_soc_eth 1e100000.ethernet eth0: Link is Up - 1Gbps/Full - flow control off

I had a similar problem with a Mediatek chipset based router. It would occasionally 'glitch' and drop the eth port and then immediately recover. Problem was it would cause the pppoe to drop. I fixed it by setting 'force link' on the advanced settings for the WAN interface. In that way it won't drop PPPoE due to a short 'carrier' ( the eth<n interface ) drop but if connection is lost for any length of time then PPPoE will time out due to LCP echo not received.

For info, I have LCP echo threshold set to 6 and LCP echo interval set to 5, so a 30 sec timeout in total

Re: Modem random drop-outs

mdubash — Wed, 04 Dec 2024 17:27:06 GMT

Thanks for the feedback. Here are the DSL stats (no errors):

Stats recorded 04 Dec 2024 17:25:50

DSLAM/MSAN type:            IFTN:0xb206 / v0xb206
Modem/router firmware:      AnnexA version - A2pv6C038m.d24j
DSL mode:                   VDSL2
Status:                     Showtime
Uptime:                     4 hours 49 min 59 sec
Resyncs:                    0 (since 04 Dec 2024 12:09:17)

                Downstream    Upstream
Line attenuation (dB):      13.1        0.0
Signal attenuation (dB):    Not monitored
Connection speed (kbps):    71131        19996
SNR margin (dB):            6.3        6.0
Power (dBm):                2.1        2.0
Interleave depth:           1        1
INP:

RSCorr/RS (%):              0.0000        N/A
RSUnCorr/RS (%):            0.0000        N/A
ES/hour:                    0        0

Re: Modem random drop-outs

mdubash — Wed, 04 Dec 2024 17:39:58 GMT

The modem's DSL light stays on and it takes just 10 seconds for the WAN connection to return. Also, there's no sign in the modem's logs of the DSL line going down - or in fact of any event at all. It is noticed only by the router, which returns this error message as the line goes down:

RT-AX58U-A5F2726-C kernel: eth0 (Int switch port: 0) (Logical Port: 0) (phyId: Link DOWN.

I've tried increasing the retries (PPP Echo Max Failures) but it seems to make little difference. PPP Echo is set to 10.

How would I set 'force link'?

Re: Modem random drop-outs

MisterW — Wed, 04 Dec 2024 18:02:16 GMT

How would I set 'force link'?

It's a check box on the Advanced settings tab for the Wan interface. The same page as the LCP echo settings

Re: Modem random drop-outs

MisterW — Wed, 04 Dec 2024 18:36:46 GMT

@mdubash using Luci goto Network->Interfaces, select Edit for the WAN interface, then select the Advanced settings tab. It should look something like this

Re: Modem random drop-outs

mdubash — Wed, 04 Dec 2024 18:46:34 GMT

Thanks - I must be going blind because I can see no such option on the WAN settings page. There's no 'Advanced' tab, nor a 'force link' option.

Edit: PS: Just discovered Luci - will investigate. Years of using the simple FritzBox interface have left me out of this loop

Re: Modem random drop-outs

MisterW — Thu, 05 Dec 2024 07:47:20 GMT

Just discovered Luci - will investigate

@mdubash did you find the setting ?

TBH I thought Luci was the default gui, I've always used it.

For info, if you need to set the option by editing the config files , its defined here https://openwrt.org/docs/guide-user/network/network_configuration about halfway down the document in the 'Common options' section

Re: Modem random drop-outs

mdubash — Thu, 05 Dec 2024 10:30:47 GMT

@MisterW wrote:

Just discovered Luci - will investigate

@mdubash did you find the setting ?

TBH I thought Luci was the default gui, I've always used it.

For info, if you need to set the option by editing the config files , its defined here https://openwrt.org/docs/guide-user/network/network_configuration about halfway down the document in the 'Common options' section

Thanks - I haven't yet explored this. I think I may have misled everyone: my router firmware is the standard Asus default, not the OpenWRT - couldn't get it to install (whole 'nuther story).

For the moment, and in the interests of time and my need to be getting on with other stuff, I've lengthened the PPP Echo Interval to 30 seconds so I'm hoping for fewer timeouts. I'll return to this asap.

Re: Modem random drop-outs

mdubash — Thu, 05 Dec 2024 10:34:34 GMT

@Townman wrote:

In the absence of helpful router stats, given that you have seen similar with different kit - consider REIN n SHINE. See Kitz.

Thanks - I've considered it but discounted it: the kit is all in the exact same location as my old FritzBox 7590 which has been rock-solid for the best part of 10 years with no drops at all and top performance.

[I've replaced it because it started making odd whistling noises, a clear sign I reckon of a chip or two starting to EOL.]

Re: Modem random drop-outs

MisterW — Thu, 05 Dec 2024 10:57:47 GMT

Thanks - I haven't yet explored this. I think I may have misled everyone: my router firmware is the standard Asus default, not the OpenWRT

Ah! that would explain why your gui is different. Looking at the Openwrt supported Asus hardware https://openwrt.org/toh/asus/start the AX58U isnt there but the AX59U is.

Re: Modem random drop-outs

mdubash — Thu, 05 Dec 2024 16:15:37 GMT

I've just had a very useful conversation with Tom from Plusnet's tech support. They've validated the back end, there are no line problems reported but they can see the frequent Layer 3 disconnects. Due to my equipment being non-standard (ie not a PN Hub), support was naturally limited but we talked through the potential options, and he eventually suggested swapping the LAN 1 and LAN 2 Ethernet ports, on the grounds that there may be a fault with the (now pretty ancient) modem's LAN 1 port.

If you're unfamiliar with the Huawei HG612 modem, LAN 1 is by default the router connection, while LAN 2 allows access to config and monitoring. So this was definitely worth exploring as an option and is what I've done, essentially bound the WAN connection to LAN 2 and swapped the cables around.

So far, 3 hours later, it's working perfectly. Another 24 hours will tell if that's fixed the problem - or at least provided a suitable workaround...

Re: Modem random drop-outs

MisterW — Thu, 05 Dec 2024 16:31:44 GMT

Whilst I've never used one , I am familiar with the HG612.

Swapping the LAN ports certainly is a useful test.

I know you're not using it, but do you actually have a Plusnet Hub 2 ? I ask because the Hub 2 can be set to 'bridge' mode and effectively becomes a modem and so could be used instead of the HG612.

So far, 3 hours later, it's working perfectly. Another 24 hours will tell if that's fixed the problem - or at least provided a suitable workaround...

I didn't realise the drops were quite that frequent, mine were a few days (sometimes up to 10) apart. Since using the force_link my PPPoE has been up for 70 days.

Re: Modem random drop-outs

mdubash — Thu, 05 Dec 2024 16:57:28 GMT

my PPPoE has been up for 70 days.

@MisterW wrote:

Whilst I've never used one , I am familiar with the HG612.

Swapping the LAN ports certainly is a useful test.

I know you're not using it, but do you actually have a Plusnet Hub 2 ? I ask because the Hub 2 can be set to 'bridge' mode and effectively becomes a modem and so could be used instead of the HG612.

So far, 3 hours later, it's working perfectly. Another 24 hours will tell if that's fixed the problem - or at least provided a suitable workaround...

I didn't realise the drops were quite that frequent, mine were a few days (sometimes up to 10) apart. Since using the force_link my PPPoE has been up for 70 days.

My PPoE was the same - with the FritzBox - which sadly doesn't easily succumb to being using purely as a modem which would have been ideal, since the noisy warbling noise mostly abated on disabling the WiFi.

I may have a Hub 2 somewhere, though I've been with PN for over 10 years so it or its predecessor are probably buried in the pile of obsolete tech junk....

Re: Modem random drop-outs

MisterW — Thu, 05 Dec 2024 17:34:26 GMT

I may have a Hub 2 somewhere, though I've been with PN for over 10 years

The Hub 2 has only been supplied for a couple of years so unless you've had a PN router since then , it will likely be a Hub 1 which can't be set to bridge mode.

NB no need to fully quote the previous post, in fact doing so will incur the wrath of the mods😀

Re: Modem random drop-outs

mdubash — Fri, 06 Dec 2024 09:47:13 GMT

Thanks for your help - glad it got fixed is the main thing. The modem will, I hope just be a stop-gap until full fibre arrives sometime Soon(TM).

PS: Mods don't want threaded discussions? Weird.

Re: Modem random drop-outs

MisterW — Fri, 06 Dec 2024 10:23:33 GMT

Its just that quoting the whole immediately preceding post takes up unneccesary space

from the forum rules https://community.plus.net/t5/Community-Announcements/Forum-Rules/td-p/1167432

General Forum Etiquette

...
Quotes are a useful way of showing which post/partial post you are replying to.
You should not quote a full post unless; (i)It’s not the post immediately prior to your reply or (ii)Your post is the first on a new page