Hi,
The issue that I am facing is very similar to following thread. I am getting certificate error and this stop Emby Android TV client to connect.
https://community.letsencrypt.org/t/problem-with-r3-expired/161818/40
https://community.letsencrypt.org/t/problem-with-r3-expired/161818/21
Can you please let me know what file I need to remove to fix this issue?
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.