Intermittent Fibre Connection

[#1]

For the last week or so my internet connection has been down for hours at a time and the timing appears to be random.
I contacted support and the suggestion is an update to the fibre modem software. But it has been working fine and only recently there has been a problem.
I am at home yesterday and today and each time I ring support the connection re-appears. This morning it was offline again, and when I had an opportunity to call its come back - hence being to post this topic!
I'm concerned that intermittent faults are one of the worst to resolve and given the looming Christmas period I don't want my kids to miss out with their tablets and consoles, especially as engineers and staff will be taking holidays too.
Any experiences you can share so that I can ask support to consider a gamut of potential causes rather than one small step at a time?

[#2]

My knowledge of weird copper faults is scant, but this kind of thing rings a bell.
IIRC, it relates to a very small disconnection in a joint somewhere, probably by some oxidisation. Whenever calls happen, the increase in voltage on the line breaks through the disconnection enough that it works again, for a while.
However, I might be thinking of cases where an incoming call is the thing that brings stuff back to life, as the AC signal used to cause the bell to ring is the trigger.

[#3]

I've asked our resident faults guru^tm to take a look at this one.

[#4]

Hi there
Our testing is showing a potential issue with the line that may need a engineer visit.
I've raised it to our suppliers for further investigation but if you could PM me three times for a engineer I can get it booked if needed.
The timeslots are 8am while 1pm and 1pm while 6pm.

[#5]

Thanks for the responses