>>13297604/tg/ guy here. I had a similiar idea, it's a setting set on a post-apocalyptic earth on which the only remaining powers are the south african, south american and australian nations but after 40 years the gene augmented descendants of the space survivors of the former nations of the northern hemisphere have returned. The Kessler syndrome did cut off physical interaction between earth and L4/L5/moon survivors for 40 years but radio would still get through but the existence of the spacers got ignored as the political implications would be detrimental to the terran governments. The few peaceful years ended as both powers claim the regions of the north for themselves and now wage war against each other.
I always wanted to make the isolation perfect by eliminating radio as well but I never got a hard scientific reason for that thus I blame politics for the willful ignorance of the new man in the heavens.