Good morning, I'm hoping someone can help me figure this out. I purchased a Vigor 166 gen2 EU version modem a few months ago house on my G.Fast connection to replace the BT provided one. For no other reason than I like tinkering with different tech.

It's been working flawlessly until around 2 weeks ago when it just started randomly dropping DSL overnight and not reconnecting causing me some headaches with the other half when she'd wake up and couldn't access Facebook

After a reboot of the 166 everything was fine and it would hold DSL then without issues at all until again some point in the early hours the next day. After a couple of days of this and me wondering if something was wrong with my line I threw the BT G.Fast modem back on and everything was fine with no overnight drops.

Yesterday morning we had a power cut and took the opportunity to put the Vigor back on and woke up this morning to the same same thing as before. Overnight DSL drop and no auto-reconnect.

I logged into the Vigor and the DSL status was just sat at READY state.

Because it's an EU version it appears I can't flash with the BT approved UK firmware so it's on the 4.2.3 STD version at the moment.

Below is the connection graph of my line with some annotations.

https://imgur.com/a/m3AxIIE

Is there something I'm missing that's causing this? I'm not convinced it's a fault unit as a faulty bit of hardware would just be faulty during the night, I'd expect to see it dropping DSL throughout the day as well.

Also, is there a way I can add the Vigor to my internal LAN to access it rather than have to grab an ethernet cable and dongle to faff about changing the subnet details?

It depends on what time it drops. Early hours in the morning = BT exchange (adjustments in SNR etc.).

There may be lots of other reasons for dropouts.

Have you tried different firmware? The BT approved firmware, to my knowledge, is one type of Draytek firmware that has been tested by BT and approved to work fine on BT lines. Whether it's the STD one or different, I can't remember (of all Draytek firmware types for Draytek routers/modems), but if you search the forum for my posts, you'll see some information about different types of firmware. For 166, it looks like there's STD and MDM1. However, I may be wrong here because I don't have 166. Those who have it can comment on what modem code BT firmware is.

My Draytek 2762 drops at 12:57am, although the past couple of weeks it hasn't, until last night. However, our line is bad and Openreach does f*** all to fix issues (10 months now! They themselves don't know what they're doing).

Thanks for the reply. I appreciate it.

I’ve tried the firmware upgrade using the 4.2.3 BT version from reading previous threads but my unit won’t take that forward upgrade for some reason.

I know that any planned BT engineering work will happen outside of normal hours. My concern is that the Vigor doesn’t pick DSL sync back up unless I do a physical reboot which is obviously not ideal.

There's a dedicated thread to 166 on the Kitz forum: https://forum.kitz.co.uk/index.php/topic,25203.0.html

Where did you get your 166? I remember having an issue using a UK modem in Europe but that was on the DSL line - there were issues with the UK being Annex A, whereas where I tried to deploy it, the standard was Annex B. The modem wouldn't work there at all. I don't know how a modem would behave in such instances here in the UK: https://www.draytek.com/support/knowledge-base/5002

Is that the reason why you can't upgrade with BT firmware?

Just a suggestion. I'm not sure.

I got mine from eBay. I’m in the U.K. but it’s an EU model 166

The modem works fine and I get good rates from it on g.fast of around 280mbps.

I’ve set it up to auto on the annex setting so that’s fine. It’s just the drop outs. I do wonder if the snr is too low on it. It’s at 2db so there’s very little buffer at all on there to absorb any spikes. But it should still auto connect after drop. So it’s that part that’s concerning me more than anything.

Well, if the SNR is 2db, then it's likely to drop out. You can increase the SNR or wait until the Exchange does it automatically.

Just a question, though: How did you switch it to auto when it comes to Annex A/B? I know Fritzboxes can work on both types of lines, but I didn't think Drayteks could.