Since the 5.8.4 software update, many Model S owners began to experience charging sessions where charging was randomly reduced from 40A to 30A. When it happens, there is usually a message on the dashboard that says "charging problems". The impact of this change is slower, and unpredictable refueling sessions. Personally, I have owned my Model S for 2 years. For a full year before the software change, I could charge at home (at 40A) unimpeded. Since the change, the software limits my charging to 30A (in most cases). The power utility has checked the install and the transformer. Tesla has checked the install. Electricians have checked the install. Everything is within standard residential tolerances (but perhaps not within the new Tesla tolerances). Lots of head scratching. Tesla won't disclose the old (or new) tolerance levels to the power utility, which makes it difficult to troubleshoot the problem. I am using the Universal Mobile Connector (with the revised adapter). Is anyone else still having this issue with the car randomly backing off to 30A while charging at home? If so, are you using the UMC cable, or the beefier Wall Connector?