One has recently upgraded (or down, depending on experience

) to a cable based internet that is very fast. The router comes with a 2G and 5G band connection. I've noticed that when even close to the router the speeds achieved are only a fifth of the 'Up to' speeds when using wifi. I'm aware of the irony that now my internet is very fast compared with the old offering, but to only get a fraction of the purported speed is a bit disappointing. A friend mused that my older laptop might only connect to the 2G band which would always restrict the speed well below, whereas another said I was likely sharing the pipe with whomever else was in the street and that would throttle the speed downwards.
I've also noticed they my IP address stays static, which countermands my assumption that these days they were dynamic, changing when you were offline or the ISP was tweaking the network etc ? Is this better or worse than dynamic ? Any wisdom appreciated.
SHJ