I replaced my EE Brightbox 2 recently, with the DrayTek Vigor 2762 (non-wireless) router. I copied the settings from the Brightbox to the Vigor and fired it up. Very quickly acquired the DSL signal and went into training. I got the Showtime message and I was online.

I am, like so many others, working from home. Throughout the last week, I have worked using a company VPN, having Teams meetings, downloading files and all the usual family stuff too, like watching streaming content. All with no problems. One week on, and watching a Netflix film for the first time since the new router was installed. It was a 4K movie, and it seems that caused the EE DSL to drop momentarily. It renegotiated and reconnected within a couple of minutes, but it interrupted the film. This happened about 6 times, until we abandoned it and turned the TV off. The connection hasn't dropped since. So, as I write this, the uptime is 10 hour 43 minutes.

It seems to suggest that when the throughput increases, and a lot of data is being transmitted down the DSL line, that the DSL drops. I am confident that my physical cabling and connection is sound. I know the connection using the EE provided Brightbox was pretty solid, and certainly didn't drop when viewing movies and all manner of other traffic. The only difference is the DrayTek Vigor. Does anyone here know of any settings that I need to check that might cause problems with the EE DSL? The only setting I changed, was the MTU setting, which was at 1520. The Brightbox was set to 1492, so I have changed that, but is seemed to make no difference. I set it back to 1520.

Any advice or suggestions would be great. Thanks.

Check the UDP flood defence settings. See Draytek's website on how to work out the value.

Firewall settings ok like 'Allow pass inbound fragmented large packets (required for certain games and streaming)'?

It's also useful to do a bit of research yourself, rather than ask on the users' forum for basic stuff and guess settings. Here, for example, it says that you should change your MTU to 1492:

https://ee.co.uk/help/help-new/broadband-and-landline/home-broadband/what-are-my-home-broadband-internet-settings

Thank you. I have trawled lots of websites, DrayTek and EE. I found the MTU value on EE, as you suggested. I also found out where the FTTC box was and the vendor (Huawei). The modem mode was set to default, but I read about operation modes (mine is G.998.4 and uses vectoring). The recommendation was to set modem mode to 779517 Annex A, which I have done. so far, the line has been up for nearly 72 hours since I made that change. I will look into the firewall and flood settings as you suggest.

Spoke too soon!

The line dropped as I posted this reply. Dammit!

1. Under 'WAN > General setup', you can select a different modem code. I found that 77B507 holds onto a noisy line a bit better (I'm not assuming that your line is noisy, by the way).
2. Check whether there's a pattern to your Internet dropping - is it the same every day? Is it when you use Whatsapp etc.
3. Calculate the UDP value and adjust this setting.

I switched to 77B507, but the DSL dropped after just one day. As far as I can tell, there is absolutely no detectable pattern, it seems completely random. Different times of day and night, low or high load, doesn't seem to be linked to any phone, computer or domestic app.
I wouldn't know where or how to calculate the UDP value?

The only way I can think to try and find the cause, would be to eliminate things, one by one, and wait for a week or two each time to be sure. If something seemed to improve or stop the dropouts, I guess I will have found the culprit. Trouble is, with so many connected devices, that would take many months, maybe even a year, to prove.

I still can't understand though, why the same devices and apps, didn't cause problems when connected via the EE router? It feels to me like there is something the ISP is sending ou, that the DrayTek cannot handle or respond to, and so the connection is terminated.