Default XTZ rooted, but ad blockers do not work properly

Hey there,

i juts got my XTZ and rooted it, using vroot (chinese app). Root check tells me that the tablet is rooted, but i am not 100% sure about that. I use adaway to get rid of those anoying ads on the web and in apps. If i install it, it ask for root permissions and installts the host file.

Browsing is ad free, but on a moment, ads are comming back and i have to repatch the host file.

Maybe its the org. kernel with problems to write at the host file?

do you have any idea what i can do ? is it possbile to go for another kernel without unlocking the bootloader over sony?

thanks a lot for your help & a happy christmas !

edit: pretty sure that /system is not rw yet, did try to fix that, but failed. anything i can do here?

edit2: it would be fine if i can edit the host file from the pc just once, without rw access from the tab itself, i just wanna get rid of those annoying ads everywhere
HTC ONE - running Android Revolution
Sony Xperia Tablet Z - running rooted stock