I don’t have 1G fibre however
The ‘benefit’ of 1G fibre is that more devices can share that bandwidth. You don’t notice day to day but when multiple people are using the internet;
- Work from Home
- Gaming and updates
- Uploading images to the cloud
- Security cameras in use
- Maybe uploading a video to YouTube
- Streaming on IPTV; Netflix, Disney+ etc
and there’s so much more that happens, all so seamlessly without a hiccup. It would be likely be just as awesome on 300Mbps too however on 1G you can burst more, especially when you need something as soon as possible.
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As for your WiFi issue. You need more WiFi points around to solve that.
The 500 vs 1000Mb debate has popped up many times, unless 1G is cheaper then stay on 500Mb.