You will need to speak to Sky as any thing installed from the ONT externally, including the ONT is the resposbility of the network provider, in the case of Sky its either Openreach or CityFibre.
If your fiber is fed overhead then they will mostlikly istall a CSP (Customer Slice Point) and extend the external fiber down your wall, if it comes from underground, then they will mostlikley shorten the existing fiber run and move your CSP to its new location.
Contact Sky on this link, phone and explain whats required. Apparently you get one free ONT move with Openreach!
https://www.sky.com/help/broadband
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I remember the Internet starting!
Sky Full Fibre & Virgin Media XGS-PON, with automatic failover using DrayTek multi WAN router.
Sky Q, which will be sadly missed when they decide to kill it off!
