this is very common problem across all Redmi phones including my Redmi 5. Immediately after Updates phone will erratic, for me Calls are getting disconnected for every 6 - 8 secs. After restart the phone for 5 times now I'm gettig better response. Surprisingly , Customer care centre persons also recommending NOT to go for all Updates. Look like Redmi team is clueless on identifying this bug and No competent person to resolve this long pending issue . Early 2 occasion of Update, mobile went to Auto restart mode for which Customer care centre just reflahsed the OS and I lost all th data stored in the phone. Now a days cautiously I move all files to laptop, then going for Updates once in 4 months. This is what I suggest you people to do. I don't think Redmi team can bring solution for your his bug.