Asus DSL-AC68U daily WAN connection drops

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StartCodon

New Around Here
I had a strange issue with my DSL-AC68U and thought I'd make a thread in case anyone was experiencing the same. Can't say it's solved, but there's a workaround for now.

The issue is very similar to that described by @my_bey in this thread. I use my DSL-68U as a modem/router on a VDSL2 connection and was experiencing drastic WAN speed drops (similar to the "outages" described in the linked thread) on a daily basis. Websites are pingable but the connection is essentially unusable because for me, the downstream WAN connection often drops to 1–2Mbps (from ~38Mbps). Only a reboot or reconnection of WAN fixes this: after that, the speed returns to normal. During the time the connection drops, the SNR margin will often more than double.

In that thread, @GNUton (who is a saint!) made a special version of his 386.2_6 firmware that contained DSL firmware 1.0.4.9 instead of DSL firmware 1.0.5.3. Both my_bey and I have tried this version of firmware with DSL firmware 1.0.4.9 and the connection drops seem to have stopped. Therefore, it seems to be linked to the DSL firmware version rather than the main firmware.

My question to anyone reading this is why this might be the case! This seems to be a rare but not completely isolated occurrence. The only other report I've seen that seems similar is here, in which someone reports a drop in upload speed using 1.0.5.1 but not 1.0.4.9. (Though I am experiencing a drop in download speed but not upload, so I'm not sure if this is the same issue.) It doesn't seem the same as this issue because the router still thinks it's connected to the internet the entire time: there's no point in which the connection fully drops out (to my knowledge).

I'm fairly certain I've ruled out QoS, errant LAN clients, and ISP outages, and it doesn't matter whether I'm running stock firmware. I've sent Asus a support note but I'm not optimistic about receiving a response. For now (and potentially the foreseeable future), I'm running this special firmware build as it seems stable.

Anyone have any other thoughts?
 
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StartCodon

New Around Here
@my_bey @StartCodon what's your ISP/Country?

I'm in the Channel Islands (outside the UK), and my ISP is JT. I think I'm connected to a Huawei cabinet if that's helpful (based on the ones I've seen around), though I don't know for sure. They didn't specify any particular settings to configure so I've left most as default -- I can ask them and see if that would be helpful?
 

StartCodon

New Around Here
Turk Telekom in Istanbul
Do you think this is the issue? Have you tried this setting in Administration > DSL Setting > Country/ISP setting? I've not tried it as it didn't seem relevant to me as I'm nowhere near Turkey, but who knows!

turk telecom.PNG


To fully test this, one of us would have to go back to DSL firmware 1.0.5.3 and enable that setting (if you've not tried it and agree it might be the fix), then report back. Would you like to do that (as it's named after Turk Telekom) or would you prefer me to?
 
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my_bey

Occasional Visitor
When I set it up on both 1.0.4.9 and 1.0.5.3, I used Turk Telekom settings as follows:
Are you saying, I should set it to Disabled?

1628538474314.png


Default selection for me was: (I do not subscribe to TIVIBU TV service so I changed it like above.
1628538647202.png
 

StartCodon

New Around Here
Here is the full settings shown on my Administration - DSL Settings page:
Ah, maybe it's not the Turk Telekom setting then; I just remember that being an oddly specific setting and saw you were on that provider. I have it disabled, so if you had it enabled and me not, I think we can rule that out as a potential cause. Back to square 1.

My settings are similar to yours but with that ISP setting disabled.

1628540132607.png
 

StartCodon

New Around Here
The only other weird thing I've noticed is that my DSL light is off on the front of the router, but the internet is working fine, speed is fine, and the DSL link in the router firmware is ok (as expected running the 1.0.4.9 build). This might be another red herring and it's not something I'd often notice because the internet's ok, just the LED that's off, but I'm just trying to spot anything weird. Don't know if you have the same, @my_bey ? Agree though that the only consistent difference between having these issues and not seems to be with the DSL firmware version.

@GNUton, if you don't get anywhere further with Asus (sounds like it might be tricky), then I don't want to ask you to make/maintain a separate 1.0.4.9 branch of your firmware just for us! I'm not a programmer but reasonably tech savvy. Is there a way we can easily make these 1.0.4.9 builds ourselves so we can run your firmware, at least until we can figure out what's going on here with the DSL firmware? Let us know how we can help out.
 

my_bey

Occasional Visitor
I just checked, my DSL LED is ON, on the front of the router.
As you suggested, it would be great if we can get a separate 1.0.4.9 branch with latest firmware updates, or not use 1.0.5.3 on latest updates as we proved it is buggy! (Wink, wink!)
 
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GNUton

Senior Member
@StartCodon you could fork the repo and use circleci to let it build the firmware, but Trendmicro won't work if the firmare doesn't get built on my circleci project.
Since when the firmware builds, at the end it generates two images by default: one with modem firmware and the other without. so If you wanna be "stuck" to an old modem firmware you can flash the image without modem firmware inside.
So it will update merlin but not the modem firmware.
If this is an option you could be interested in let me know and I can publish the image without modem too along with the onewith modem inside on each release
 

StartCodon

New Around Here
@StartCodon you could fork the repo and use circleci to let it build the firmware, but Trendmicro won't work if the firmare doesn't get built on my circleci project.
Since when the firmware builds, at the end it generates two images by default: one with modem firmware and the other without. so If you wanna be "stuck" to an old modem firmware you can flash the image without modem firmware inside.
So it will update merlin but not the modem firmware.
If this is an option you could be interested in let me know and I can publish the image without modem too along with the onewith modem inside on each release
That sounds perfect, thank you so much! Updating Merlin but not modem firmware sounds ideal. Thank you for all your help on this.
 

GNUton

Senior Member
Hey there,
now you should be able to download images without dsl modem firmware too along with the complete ones.
Again.. flashing the no dsl firmware will make your router stay on the old modem firmware.. so it should work for you.

DSL-AC68U_386.03_2-gnuton0_beta4_DSL_1.0.5.3.trx
DSL-AC68U_386.03_2-gnuton0_beta4_NO-DSL-FIRMWARE.trx
 

StartCodon

New Around Here
Hey there,
now you should be able to download images without dsl modem firmware too along with the complete ones.
Again.. flashing the no dsl firmware will make your router stay on the old modem firmware.. so it should work for you.

DSL-AC68U_386.03_2-gnuton0_beta4_DSL_1.0.5.3.trx
DSL-AC68U_386.03_2-gnuton0_beta4_NO-DSL-FIRMWARE.trx
Thank you! Found the _NO-DSL-FIRMWARE file. Haven't managed to test it so far because I don't have access to the router at the moment but will give it a try at some point and let you know if there are any problems. Cheers!
 

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