You will need to check the time on the system. Most probably your Rasp is issuing the wrong time to the OS and the Certs become void. Issue the date
command and check the time. If it is wrong issue
sudo date new_date_time_string
where new_date_time_string has to follow the format MMDDhhmmyyyy.ss which is described below:
MM is a two digit month, between 01 to 12
DD is a two digit day, between 01 and 31, with the regular rules for days according to month and year applying
hh is two digit hour, using the 24-hour period so it is between 00 and 23
mm is two digit minute, between 00 and 59
yyyy is the year; it can be two digit or four digit
ss is two digit seconds. Notice the period . before the ss
With the proper time in place. It should most probably solve the issue.
Source: What is the command line statement for changing the System clock? && I ran into the same problem with my Beaglebone