I've heard of a similar issue with a wireless data link across a river that would cut out once or twice a day, but not everyday, and no one could figure out why

I've heard of a similar issue with a wireless data link across a river that would cut out once or twice a day, but not everyday, and no one could figure out why. The answer only came after a few weeks of monitoring and an ametuer fisherman saying "hey, those are all high tide times!" at which point they realise that high tide was causing the mast of a docked boat to rise up enough to interfere, and that the boat was not always in its dock which is why some days were fine.