4g doesn't seem to be working - s20 ultra (5g)

[Jak]

I've just bought an s20 ultra 5g as I broke my s20fe. I put the sim in the ultra and 4g doesn't seem to be working. I put the sim in another phone to check if it was poor coverage/signal but 4g showed up straight away. I've checked the network settings, it's currently on "GLOBAL" do I need to change it? There isn't a 4g option. It's not a 5g sim/ tariff so wouldn't get 5g.
Is there something I need to do manually to get 4g going?

[Cleoriff]

@Jak 

The 4G issue shows a fix in this article..

https://thedroidguy.com/galaxy-s20-no-4g-lte-signal-easy-fixes-1124573 

[Martin-O2]

Hey @Jak how are you getting on with this issue? 

[Jak]

Hey Martin, I'm going to return the phone. Had no joy connecting to 4g, every so often I get LTE but it's literally for seconds then drops back down to h/h+. After checking the processor and csc code, it turns out its the American build.
It's a shame as the snapdragon chip is miles better than exynos, the phone is mega responsive and the battery is unreal (took it off charge at 8am and it still has 38% now - 9.30pm - that's with relatively heavy use)