Hi there,wondering what's the best system to use to get Internet connection, just been to a festival with zero connection for 4 days ,what set up is best ,thanks

Mobile phone hotspot, if you have a data package as part of your contract, is the simplest option.

Buy yourself a Mobile Router with an external Antenna. That will pickup a 5g signal of up to 2 miles away.

Always a good one D-Link F518 Portable WiFi 6 5G NR/4G LTE Cat 12 Router w/ Embedded SIM Slot (1.7Gbps AX)

Last time I went to a festival-in-a-field, the local mobile network had signal but was completely saturated because it wasn't designed for XX thousand people showing up at this rural location. That's a different use case from regular camping where there's few other people about.

Might be worth looking at Starlink. They keep changing the prices and terms but I think on some of the packages you can switch it on and off - ie don't pay the monthly fee when you don't need it.