On May 3, 2021 PayPal will update the list of IPs for their Instant Payments Notification (IPN) service.
Here is the list of new and old IPs:
18.104.22.168 (Old) 22.214.171.124 (Old) 126.96.36.199 (Old) 188.8.131.52/24 (Old) 184.108.40.206 (Old) 220.127.116.11 (New) 18.104.22.168 (New) 22.214.171.124/21 (New) 126.96.36.199/22 (New) 188.8.131.52/22 (New) 184.108.40.206/20 (New) 220.127.116.11/23 (New)
You should add the new IPs to your firewall/allow lists to ensure the normal operation of the PayPal notifications for your account.
The clean list of the new IPs to add to your allow list is:
18.104.22.168 22.214.171.124 126.96.36.199/21 188.8.131.52/22 184.108.40.206/22 220.127.116.11/20 18.104.22.168/23
If you are using csf just edit the /etc/csf/csf.allow file and add the above IPs.
# nano /etc/csf/csf.allow
# csf -r