Very late to the party on this thread, I haven't been on the forums in quite a while, other than yesterday to boast about getting on board for the 20 Ultra after skipping the 10.
Anyway, I'm on VZW and have done all the software updates as they've come, and haven't had this issue, but When trying to plug the phone into my bike the other day to try out Android Auto for the first time, I noticed that my port must be fudged somehow because just looking at the cable the wrong way will make it lose it's connection. I haven't used a cable in quite a long time as I just wirelessly charge overnight every night. I tried a few different cables, and no matter what, just the most minor touch or movement of the cables will cause disconnection. I'm not sure how, or why, or even how long this has been an issue, and it's nothing major, but was wondering what your ultimate outcome has been. Was it really firmware, or something physical with your port?