@Rscragg a little background your Mum's line looks to be very long so the potential for issues is increased. Its not Sky who set the 10 drops per 24 hours its Openreach who own and maintain the lines as you can imagine they are not going to sort a couple of miles of possibly over 30 year old copper line unless they have to.
The stats look like a limit has been applied in an attempt to stabilise the service but frankly VDSL was never designed to operate. over such long lines. Given the sevice delivers well over the current Universal Service Obligation of 10Mb/s means options are limited until fibre is run the properties near your Mum.
The reason why the connection test is worth running is it knows the history and can book an engineer to check the line. The test can be run from anywhere and will return the results for the line linked to the Sky id used to log in so asduming you know your Mum's Sky id log in you can do thst remoretly. If contacted Sky will run the test from their end to see if Openreach will accept a line fault.
It is also worth checking to wiring in your Mum's home the hub should be connected to the master socket not to an extension and a good line filter being used unless the master socket is the pre-filtered type with 2 ports one for voice and one for dsl. The modem cable should be under 10m ideally and in good condition..
Hopefully you can get the line checked
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65inch Sky Glass, 3 Sky Streaming Pucks, Sky Ultrafast + and Sky SR213(white Wifi Max hub) main Wifi from 3 TP-Link Deco M4 units in access point mode
