Unable to access server from one specific ipad only, it works from all others and iPhones.

My wife is a regular online shopper with H&M in the UK.

Suddenly, and for no apparent reason, she keeps getting this from their servers when following links in emails they send....

You don't have permission to access "http://www2.hm.com/en_gb/member/info.html" on this server.

Reference #18.44997a5c.1591086378.1b78d5e0

This ONLY happens on her IPad Air 2.

It does not happen on her iPhone SE, nor if the email is forwarded to my IPad Air 2, nor my iPhone 6S. All devices are at the same OS level 13.5 although it was happening before her devices were upgraded from previous level.

I have cleared cache and history for Safari, erased all recorded sign-in data in Keychain, re-booted several times. It still happens ONLY in her iPad.

I have spoken to H&M technical support. They say their are no problems at their end, which I believe as everything works OK on other devices.

Any suggestions as to what I can do to clear this?