here is the fix 1) Find where root certificates have been stored in your Qnap, mine was in /etc/ssl/certs cd /etc/ssl/certs ls -lth | grep DST_Root_CA_X3.pem rm -f 2e5ac(whatever your symlink is) rm -f DST_Root_CA_X3.pem 2) Copy these two files in /etc/ssl/certs https://letsencrypt.org/certs/isrgrootx1.pem https://letsencrypt.org/certs/lets-encrypt-r3.pem 3) reboot your qnap.