iOS 6 - 4G celluar problem - some app open problem

[Bertodello]

I wanted to ask for some help regarding my setup. I have an iPhone 5 running iOS 8.x.x, and I installed the latest version of Coolbooter to run iOS 6 alongside it. However, I’m facing a couple of issues:

Some apps won’t open on iOS 6—they crash immediately when I try to launch them.

The 4G toggle is missing; only a 3G button is visible, so I don’t have 4G connectivity.

I was wondering if these issues can be solved with Coolbooter, or if perhaps the tethered boot option in your iOS Kit could help. I also noticed that the iOS Kit includes a baseband update—could that fix the 4G problem?

Lastly, could you recommend any guides or videos showing how to create a small Raspberry Pi–based tethered boot tool for tethered downgrades?

Thanks so much in advance for your help!