"Connexti" would actually be treating it as a Latin, not a Greek root (as a noun from the second declension, except it can't fit that model since it doesn't end in "-us."
) Neither Latin nor Greek roots can account for a noun ending in "ext." Even an irregular Latin noun wouldn't end like that...
If I were saying it, I'd just fall back on my choral training and say "Connexts" and focus on enunciating "ks-t-s" as if it was being sung.
Or, if I wanted to not do that, we could hereby designate the plural of "Connext" as "Connext" (treating it as if it was a fourth or fifth declension Latin noun.) "Connexus" makes me think of a bunch of them being the focus of something. So maybe if it were a LARGE group of Connexts that people were congregating about?