I had to reinstall and wipe to get onto OTA-16 for some reason, but I'm not having the issue where calls / SMS aren't coming in after not restarting for 8 hours. It's been receiving and sending SMSs for about 18 hours. So I assume the issue is resolved. My 4G is still intermittent for some reason after updating the APN settings for my Ting with my credentials. I haven't tried reverting back down to 2G / 3G.