Plusnet Hub One Firmware update
Yeah, that's what I figured, too.
As an aside(?), since the firmware rollback, the line speed has dropped from 53/10 to 46/7, which makes we think the line is now being pegged back. Especially as Support stated that the guaranteed line speed was 46. (I have the top package, but, obviously, I never expected to get 75! 
)
Another oddity is that the router has been stable, except...
--- Boot Log extract ---
01:02:25, 20 Sep. ( 31.750000) System up, firmware version: 4.7.5.1.83.8.237.2.2
01:02:09, 20 Sep. ( 16.230000) System start TR069
01:02:29, 19 Sep. ( 30.300000) System up, firmware version: 4.7.5.1.83.8.237.2.2
01:02:15, 19 Sep. ( 16.220000) System start TR069
21:48:11, 18 Sep. ( 30.720000) System up, firmware version: 4.7.5.1.83.8.237.2.2
21:47:56, 18 Sep. ( 16.140000) System start
--- End ---
21:47 is when you did the rollback, but how strange that the router reset with that TR069 at exactly the same time 2 days running. Hm...
@bobpullen wrote:
I've got a feeling that's a result of the rollback. When we tag your device as part of a coordinated upgrade, there are two actions:-
- Instruct the router to download the firmware image (happens during the day)
- Schedule a reboot to apply the firmware image (happens ~1am)
My guess is that there's some logic during this stage of deployment that says 'If device has been tagged, and firmware version != 4.7.5.1.83.8.259.1.1 then schedule reboot.
If I'm right, this is likely to continue until the rollout is complete and a proper activation policy enabled for the new firmware.
It should also go away when we upgrade you again to the latest build
That was my take, too, but thanks for confirming it.
@bobpullen wrote:The reduction in sync speed could be due to the inferior DSL driver/subsystem used in the older firmware.
That would make sense except that those higher speeds were with the current version before the update and were maintained afterwards. Of course, I don't know if the software at the other ends has detected the rollback & figured something is wrong so pegged back the speed to be on the safe side.
Re Engineer Visit
BTW I got a call earlier today and when I answered a bloke says hello then hangs up on me. I get loads of Phishing calls so I check the numbers before I add to my call blocker. Turns out it was a BT Openreach number, but he never called back.
PS
As I typed this we had a power cut! So if you check the line again, this is why the router reset just now. This is a regular occurrence in bad weather around here. I suspect most of those drops you saw before the firmware update were due to one of those. 
Damn
Right, I've rolled the firmware back and arranged for a replacement device to be shipped to you. the device will be running 4.7.5.1.83.8.259 out of the box, however we can upgrade to 4.7.5.1.83.8.259.1.1 once you've hooked it up. That said, the wi-fi elements of the firmware are identical between the two versions.
Keep hold of the device you currently have and *don't* send it back using the returns bag you'll be sent. I may need it back here in the office for analysis.
Ok thanks.
I figured you'd done that when all my networked devices failed - printer/NAS, for example, have fixed addresses because some devices on the n/w can't cope with name only. For some reason, rolling back the firmware resets the n/w address to the default. The PC copes fine with the 1.254, but bizarrely doesn't like to be put back to 0.16.
I suppose I could use the router default, but 30 years of using 192.168.0.xx is kind of ingrained in my psyche. ATT most of my (BT engineer) friends used to use 10.0.0.1 instead. Back then, many routers defaulted to that, but it seems 192.168.1.xx is the norm these days.
Another reason I change the defaults, of course, is because I'm paranoid and it makes the router a tad more secure (in theory!). 
Okay, so the router has now been up for around 2 hours with 4 devices connected to wifi. Somewhat better than was achieved when updated to 259.1.1 last time (40 minutes). As you said, it has 259 out of the box, so I assume it'll be updated at 1am tomorrow morning. Perhaps that's the one to watch.
PS
The router didn't arrive with a return envelope for the old one.
Well, over three hours since the update and the router seems to be behaving.
There are currently 3 devices connected to 2.4Ghz and one on 5GHz. I have separated the two channels, so they aren't linked and changed the SSID/Password to my preferred settings.
Although there are four devices connected, they aren't really doing anything at the moment. So it'll be more of a test later when my daughter gets home!
As an aside, re old router:
I can't say for sure, but I feel that the new router, although warm, is not getting as hot as the old one did. On reflection, I thought the old router had been getting a little hot recently. I also made sure to use the new power supply when I swapped the routers over, just in case the old supply was dropping out.