The problem is that patches we need are only in kernel 5.0 (or maybe even newer). We have patchset for Linux 4.19 but not for 4.14. The problem we are currently in discussion is if we should backport kernel 4.19 or patches on 4.14.
Original idea was to migrate all Turris 1.x users directly to TOS 5.x and just skip 4.x but upstream decided to stick with kernel 4.14 with OpenWRT 19.07 so we are out of luck there. This means that we now have to decide what will be our approach and we still are in discussion about that.