Paypal payment notification refused: IP not valid for the order

-- HikaShop version -- : 5.1.3
-- Joomla version -- : 5.2.4
-- PHP version -- : 8.3.16
-- Error-message(debug-mod must be tuned on) -- : No error message on page as it occurs later in processing

After a purchase via PayPal Hikashop sends an email with subject line:
Paypal payment notification refused: IP not valid for the order XXXXX
The body of the email is:
A Paypal notification was refused because the IP 173.0.81.140 is not in the list of valid IPs :
146.75.45.*
173.0.81.*
173.0.93.*
173.0.82.*
173.0.81.140
The problem is that the IP used by PayPal IS in the range of valid IPs.
I've followed the advice in www.hikashop.com/index.php?option=com_up...ment-paypal-error#ip trying to address this for earlier purchases and it doesn't appear to work..
What is the way to resolve this?

Thanks, Nicolas - done.