Permalink structure on different devices

I have a Permalink-problem with a recent website of mine (http://www.zomerschool.eu). When viewing and using the website on my computer, all the Permalinks for the Custom Post Types work fine; it has put out the /%custom_post_type%/%year%/%postname%/ structure I wanted. However, when viewing the same website on different devices (mobile phone, other computer) the same Permalink structure puts out a 404. If I revert to the default /?p=123 structure there are no 404s. I have searched for it, found certain solutions, but nothing has helped yet. What should I do to resolve this problem?