@SeanD4 & @MarinersAve apart from being quite technically difficult for an isp to throttle speeds there is no evidence Sky do - not sure of Ireland but in the UK the various speed test would quickly notice any such activity and it would be big news - as there is no gain to them by doing so.
However there are several other causes of speed issues. The first is contention which is caused by the link to the exchange being shared by multiple customers all of whom are using the capacity while actually pretty rare it is possible on full fibre connections as in the most common full fibre system (GPON) up to 32 customers share 2.48Gb/s download from the exchange. In Ireland Sky use multiple network providers including EIR, Virgin Media and SIRO these issues are local.
However by far the most common issue is wifi signal level in the customer's home being affected by factors like interference from neighbours' networks which is often worse during peak times. Improving WiFi signal levels either by being closer tomthe hub or by getting additional equipment.
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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
