Missing holidays calendar and calendar says no internet connection
I used to have the holidays calendar on my iPhone, however sometime after new year, all holidays disappeared from my calendar. The holidays calendar is no longer shown in the calendars overview. It's not possible for me to add it again through "add calendar". When I try to refresh my calendars on the page where you can also add new calendars, I get the error "no internet connection" even though the internet is working fine with all other apps. Does someone have an idea how I could solve this problem?
iPhone 13 Pro