Best router for o2?

I am looking at getting 4g broadband for a relative, in an o2 controlled area of the country. I believe that the area has 2300mhz from o2 so looking for a router that supports that and i guess ideally carrier aggregation on o2 also.

Grateful for advice.

Sadly I have tried EE vodafone and three in the area in an ipone and the speeds were shocking so they arent currently an option.

Thanks