Plusnet Hub 'broadband' light question

[#1]

Hi,
I've noticed my Plusnet Hub 'broadband' light isn't illuminating today. Yet the 'Internet' light is on/flashing, and my PC connection and speeds are fine.
The reason I am a little concerned is we have another hub connected which is linked to our central heating: Called the PassivSystems hub. It doubles as a thermostat to set our heating and our solar power supply. Without it, we can't switch on our boiler and use our central heating.
I've also noticed the PassivSystems hub red warning light is illuminated, suggesting the communion for our thermostat and central heating isn't connected - the red warning light wasn't illuminated when the Plusnet 'broadband' light was illuminated.
Should the Plusnet Hub 'broadband' light be lit when I have broadband connection? And if I do have a good connection, which I have, why is it not lit?
I hope all that makes sense and I will also contact PassivSystems for their advice too.
Any further help or advice would be appreciated.

[#2]

Quote

I've noticed my Plusnet Hub 'broadband' light isn't illuminating today. Yet the 'Internet' light is on/flashing, and my PC connection and speeds are fine.

If the speeds and connection are fine, then I wouldn't worry too much about the lights. The broadband light normally indicates the 'sync' between the router and exchange, however as this part is handled by the Openreach modem on fibre this light doesn't really make any difference.

[#3]

Thanks for the reply. Although my issue is a little more specific as this seems to coincide with my Central Heating Hub not being connected now, like I said in my previous post - I thought it may come across a little confusing.
When we switched to Plusnet began last week, and I connected all the hubs and BT Router together, the 'broadband' light was illuminated and the PassivSystems central heating hub was connected, so we could access our central heating.
Interestingly, a BT engineer came out the other day to check my phoneline and repair a fault at the cabinet, but I didn't notice after the repair whether this changed the behaviour of the Plusnet 'broadband' light and therefore my central heating connection to it - I only noticed the central heating hub 'red' unresponsive light this morning.

Like I said, without our central heating hub being connected to the internet, we are unable to switch our heating on. Obviously if this was during a winter period, a solution would be vital, so any further help or advice would be appreciated.  

[#4]

Update:
I've been searching for possible reasons why the Plusnet Router broadband light is not illuminated and whether it is contributing to my central heating hub's lack of connection.

Just to reiterate, when I first connected all the Routers together after my switch to Plusnet last week, the Plusnet Router broadband light was illuminated and my central heating hub was connected and working.
Since a BT engineer repaired a phone fault on Thursday, I didn't notice the Plusnet Router broadband light has been unilluminated until Saturday morning. According to the attached image, apparently this means the Plusnet Router is not connected to the BT Openreach modem.
Obviously, it remains curious why I still have internet connection and decent speeds, according to the tests I have done. However, I wanted to check something else.
We also have Sky and the On Demand feature using wifi connection. In the past, downloading On Demand programs has been swift due to our high speeds. However, I am still waiting to download a two hour programme and after a two hours waiting, not only have I been given the option to view the programme whilst it downloads as I usually am, but only 57% of the programme has downloaded - after two hours!
This test alone tells me something isn't quite right. Usually, our wifi speeds are as good as our cable speeds, so perhaps this is evidence that my fibre isn't working as well as it should be, and the lack of a green broadband light on my Plusnet Router is showing me something is wrong. 
Any further help and advice would be appreciated.

[#5]

Have you tried restarting the Plusnet router?
Best not to restart the BT modem, but the router may benefit from a restart.

[#6]

Thanks for the suggestion. I've tried resetting the Plusnet router a few times, but it doesn't seem to resolve the broadband light query. I think if the broadband light hadn't illuminated when I first connected everything together after we switched, I wouldn't be as concerned. Plus, the Plusnet online troubleshooter suggests the lack of a broadband light on the router suggests I'm not connected to the BT Openreach modem correctly, but I must be to be online and receiving fibre speeds. It's all very confusing.

The good news is, after speaking to the central heating company, their hub's lack of communication was a fault at their end and it's now been resolved - dunno why I wasn't made aware of this without contacting them. Thanks for all the help in the meantime.

Having had broadband for many years now, I come to learn one issue can sometimes have numerous causes, and it also didn't help that my Sky TV Wifi box has been having communication issues with the Plusnet router too - I find I keep having to reset the configuration, and re-enter my password.

However, I've just tried to download an On-demand programme and it downloaded it fine, so I have no idea why there was a download problem yesterday.
Thanks again.