As far as I can tell they offer it. I’ve tried using x.ispsn witch is a sprint apn specifically for ipv6 and fast.t-mobile.com which I think is for both and r.ispsn which i think is ipv4 only. In qmi mode it doesn’t connect at all and I don’t get assigned any up address but in qcm mode at least I get an ipv4 and it says “unable to get ipv6 address”. I have ipv6 enabled from the gl.inet menu on the modem_1_1 interface and I don’t think I’ve changed anything in Luci yet.