There are two types of 5G connectivity that are used for routers and masts to negotiate a 5G link:
NSA (none stand-alone) NSA means the router and the mast must negotiate a 4G link before it can negotiate and use 5G. Once negotiated it will still require a link with 4G despite using 5G. Basically the operator attached a 5G radio to an existing 4G mast so its not pure 5G like SA (cheaper for carriers to install).