Symptoms
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Websites are periodically inaccessible with the following error shown in web browser:
502 Bad Gateway
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The following records can be found in the
/var/log/fail2ban.log:# for i in $(plesk db -Ne "select ip_address from IP_Addresses"); do grep $i /var/log/fail2ban.log | grep Ban; done
2021-06-07 11:52:15,036 fail2ban.actions [2591]: NOTICE [plesk-wordpress] Ban 203.0.113.2
Cause
An IP address used by the server is added to Tools & Settings > IP Address Banning (Fail2Ban) because the server IP is missing in the list of trusted IP addresses in fail2ban.