The fibre network (mostly) belongs to either Open Reach or City Fibre, it doesn't belong to VF. If you mean the router, they generally work for most people, but if you're doing something less common the lack of flexibility in configuration is going to be an issue and you may find getting your own router is better. Do note that most people post on here with a problem, so it's not representative of the whole of the VF product.
If you type your question into an internet search engine you'll find some independent reviews.
