If your device does not display any image, it can be caused by outdated OS installed on the device. If the issue is caused by expired CA, it can be resolved by installing the ISRG Root X1 to the device trust store.
iOS 9.3.5/Mac
DST Root CA X3 expired on Mac/iOS is an error that many Mac users have likely started seeing in their browser since the 30th of September. The background image and logo are not displayed due to expired Let's Encrypt CA in outdated iOS version e.g. iOS 9.3.5.
In general, the steps below can help to resolve the issue.
Download the ISRG Root X1 certificate file from http://x1.i.lencr.org/
Install ISRG Root X1 certificate to the trust store (Always Trust)
