OP here.
Firstly, apologies for not having kept up with this thread. Didn't receive any notifications. I'll sort that.

Very interested reading all the above regarding SteveM84's issues.
Some comments rang a bell with my earlier experiences. Especially the PSU, and the possible incoming VoIP call. 
I do wonder if changing public IPs was involved. 

My follow up is that I surrendered to the bigger priority. I gave up using the VoIP facility and factory reset the router.
Then I also bought a Gigaset N300IP unit to deal with VoIP.
Since then I've had no problems at all.
Around the same time though, I also gave up the old ADSL line, so it's only operating now with the CityFibre FTTP. 

Ref the possible PSU connection. I'm still using the same PSU that I had swapped in as mentioned previously. And as I say, no problems now at all for many weeks.

Best wishes to SteveM84 hoping you do solve whatever was happening. I'm no stranger to having to drive dozens of miles for this stuff.
And to those others contributing in the thread.


 

Hi john, thanks for your good wishes.  I have been lax in updating this forum regarding my issue as I raised the problem with Draytek support who passed the logs on to an engineer.  They said that the ISP was not responding to LCP Echo and suggested the console command "internet -R 30".  That seemed to work and I have had 10+ days of connectivity since applying it.  However today I have lost connectivity again since the router rebooted at 1am this morning.  I do have a brand new PSU in my hands and will connect that tomorrow evening when I make a visit but I don't think it will make much difference.  I too have a grandstream for the VoIP calls and would not have thought they could really affect the router, but I did see the router noticing the VoIP packets and making self-initiated change to QoS because of them.  One thing I changed recently (which I remember only now that I am writing this) is that I turned on traffic graph (I think it is called) that allows me to see what devices have registered on the LAN from the dashboard page.  When I get a connection (or tomorrow during my visit) I will turn this off as it interacts with hardware acceleration and may be responsibe for the latest disconnect.  Maybe it is time to invest in a newer model afterall as this one has been installed since 2018.  Then there is the dilemma of which model - I think a 2927 but should I get the L version with built-in mobile data, and would that definitely allow me to connect remotely if the main fibre WAN is down (I am thinking of CGNAT as someone pointed out to me earlier).

Steve, a 1am reboot (are you sure that is what has happened?) may relate to some network change by Openreach/the ISP.

Does your connection to that router rely on an IP address or some other means (Dynamic DNS or similar)?

I don't think you will find that hardware acceleration is related to the problem.

As for the 2927L, if you get a moble operator with a public IP address (most use CGNAT) you stand a chance of making a connection (but obviously you need to know the IP address on the mobile connection you are connecting to).

Also Steve, what does the last 24 hours of the Think Broadband monitor look like (over the reboot)?

Regarding mobile connection:
Solwise do a range of 3G/4G Fixed IP Sim Cards. These are not cheap - starting @ £21 + vat per month, but knowing Solwise I'd be sure it was a reliable service.
 

@markhawkin, yes its a scheduled reboot at 1am. My thoughts being if its in disconnect mode then a reboot will stir things up and maybe get a connection again.  I have dynamic dns AND static IP address (I have also seen a large increase in the traceroute and scan warnings since the static IP).  I was hoping if it switched to the mobile then it would also update the DynDNS but obviously CGNAT would put paid to getting in from outside except perhaps using the VPNMatcher service, not sure if that would work
@john - thanks for that I had no idea such a thing existed, however the cost seems a bit high for me to use one as a backup to the fibre, even if it did mean I could get into the router at any time.
As for the thinkbroadband monitors, here is the one from last night showing the tail end of a 24hour outage and the 1am reboot.  It looks like the reboot IS NOT what reconnected it as there is half an hour or so of disconnect after 1am, but it did come back to life just before 2am
https://www.thinkbroadband.com/broadband/monitoring/quality/share/3c333a599b90f6d7a10515ac84cd17151dff40d6-01-10-2024
This is the live graph (I think)
https://www.thinkbroadband.com/broadband/monitoring/quality/share/bdc261205ef48dac6f2789154471f10c6214aed4