This is driving me mad and i cannot figure it out.

I have a 2862ac and a brand new 2866ax - both are suffering same issues, so i'm pretty confident its not the router, but i'm totally baffled.

Sometimes after a few days, or just minutes the router will dissapear from the network and there will be no connectivity to it or the internet - it cannot be pinged and does not respond via browser to 192.168.1.1

All was working fine for months then suddenly the 2862 would just dissapear, and then come back randomly after a few minutes - this would sometimes happen multiple times before becoming stable again. Ocassionally it would never come back and power cycle was the other thing.

Got a new 2866 and this is acting exactly the same.

Used new power supply/patch leads etc., swapped everything physically i could. I've got a few switches around the house and restarted all of these. 

What is baffling me is what can make the router seem to totally crash to the point it cannot be found/ping'd etc., but will then recover and carry on like nothing happened sometimes for weeks.

Once it has crashed i just plug my pc and dsl connections only to it, and it still remains non functioning for a period of time before it come back alive...

I am by no means any kind of IT expert, just a long time Draytek user over the last 20 years..

Just waiting for it to come back again so i can post this

I would insert a USB memory stick in the router and on the DrayTek router's web page visit "System Maintenance/Syslog" and ask the router to send its syslog to the USB disk. You need to select what syslog information you want to record to USB, ensure "Router/DSL information" is, at least, ticked. No harm in ticking more though. Then wait for the issue to occur again and post the events, recorded on the USB stick, just before the outage here so we can see what happened.

The USB disk needs to be formatted as a "FAT32" disk on a computer before installing in the Draytek. I leave a USB drive running on all of my DrayTeks to record syslog, just in case I get an issue.

You mention you have multiple switches around, is there any chance you could have a loop somewhere? It is very important, on ethernet, that there is only 1 ethernet path to any device. If there is a potential of a loop in the system then it will kill the network. There are ways to manage this, such as spanning tree, but for simple use this is not normally necessary.

I have a colleague who see's this exact issue with a 2927...he's pretty much nailed it down to 'something' his SkyQ and miniboxes are doing with their bizarre network stack - if he unplugs them when the issue happens the Draytek re-appears straight away.

Do you have Sky on the network ?

Thanks Ian - thats interesting - yes, 4 x skyQ boxes on the network

Thanks Andrew - i'm setting up a usb stick now.

I've double checked all the switches to ensure there is no loop

Once i've got some results i'll post back here

By any chance are those Sky Q boxes a mixture of hard-wired and wifi ?

The thinking being that a mix like this definitely has scope to behave badly because of how the Q boxes attempt to create their own mesh network especially if you have just some of them hard-wired - you've then got potential for loops - possibly.

If they are all hard-wired you could force the wifi off on them all from the service menu on the boxes themselves - wouldn't hurt to try...