The below steps will resolve your issue at the cost of waiving the operating system’s ability to block signatures revoked for legit security reasons. If you have previously tampered with an affected system, please revert to the most recent Time Machine backup (no manual signature-stripping or hauling around of system files).
Step 1. Physically disconnect the affected device from the web. Powering down the router for a few minutes will do just fine.
Step 2. Boot into
Safe Mode. Everything will be extremely laggy, be patient.
Step 3. Launch Terminal and enter the command ‘sudo nano /etc/hosts’, once prompted provide the password.
Step 4. Append the following lines to the file’s contents:
127.0.0.1 ocsp.apple.com
127.0.0.1 ocsp2.apple.com
127.0.0.1 ocsp.digicert.com
Save changes and exit.
Step 5. Run the following batch of Terminal commands:
crlrefresh rp
sudo rm -f /var/db/crls/*cache?.db
sudo date -u 020200002020
sudo reboot
Your computer will immediately reboot after the last command. Upon seeing the desktop again, you should notice that everything is back to normal. You can now reconnect to the internet. System time and date will automatically adjust themselves upon reconnecting. If some apps throw errors related to bad time and date, another reboot will fix that. Don’t worry if you run into any scary messages upon the first reboot.