Speed Test Api Error

Everytime I try to check the Website Speed I get this error:
API Request Failed: GET /api/v4/zones/04f10f5256222ee9b2cb80e08df1baab/speed_testing (504)
Can someone help me ?

Thanks

Is that in a little red bar across the bottom of the screen? The only other related topic I see with a 504 during a Speed Test is this: