Are there multiple translations for 不上边?
There's two things going on; a verb (碰边 or 沾边) and an auxiliary verb (不上) inserted in the middle.

碰边, 沾边 literally mean "to touch the edge", which is a metaphor for relationship. 不上 means "unable to" in this context (similar to 不到 or 不得). So altogether, 碰不上边 means "unrelated".