Your ISP is most likely getting its service from one of the major providers (AT&T, Comcast, etc) via fiber to their main facility and then managing their network from there.  I can almost guarantee that your service issues are not coming from your providers provider because if they were half the country would be complaining.  To better answer your questions we will need some more info but here is a start.  It sounds like your internet is provided to you wirelessly and coming off a tower that multiple companies use.  So you have a radio on your property that is pointing to a radio on the tower.  Are you the only customer having issues? Do you know any other customers using the same provider as you?  Are they having issues as well?  Do you have clear line of sight to the tower?

Using a different ISP off the same tower could yield drastically different results.  A different provider could be using a different frequency to send signals to your house.  They could be using different technology to get the service to the tower (wire vs. wireless).  They may have a different saturation level of users on the radios facing your house, etc.  There are so many variables to consider that it may be worth having a conversation with a different provider.

You say you have 5G service.  I really hope you mean 5MB service because if its 5G service its really special........because 5 GB wireless service doesn't exist.