US LTE bands on European Lg g flex 2 H955?

Hope somebody has a solution for this. I brought H995 from europe to us hopping to use it on at&t. I'm rooted so there is no problem accessing hidden menu where LTE bands can be enabled, however when i click on bands 2, 4, 17 i get FAILED. According to some this means that bands are enabled already. The problem is that device connects only wiht HSPA+ and not LTE :( LTE Discovery shows that LTE is not available. Speedtest shows that download speed is 9,91 Mbps - upload 1.29 Mbps - its not bad, but still not LTE.
Love the phone after rooting, debloating, and changing heat profile - runs great.
So the question is - can something be done to get LTE?
Thanks,
Romas

H955 root

Currently running root on 5.01 however wanted to upgrade to 5.1.1 root as I've heard its has much better performance, first question is do I need to unroot and upgrade via ota update then root or can I go straight to rooted 5.1.1? Second question is whether one of the people working on the root could upload a separate thread with detailed instructions of how to root as I find it almost impossible to navigate my way through the development thread, sorry if this seems demanding.
Thanks for the help!

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