Beginner problem with 404 on home page

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Hi, I've just realised my site at bowmenofbackworth.co.uk doesn't load on android browsers - the home page gives a 404 error (and the home link on the 404 page loops back).

As a temporary kludge I've put in a custom 404 page with a working link, but obviously less than ideal. Can anyone give me a clue as to what's happening?