My guess - US holiday. The time for the drop in traffic chimes with the usual period we have to jump on Trans Atlantic zoom calls. So this day there was a lack

My guess - US holiday. The time for the drop in traffic chimes with the usual period we have to jump on Trans Atlantic zoom calls. So this day there was a lack of those calls and hence a drop in normal traffic. NI is worse because it’s the hub for UK and even European trans Atlantic traffic. It’s hard to say as this is not measuring packets but weird sort of CDN proxy effects and I am just guessing :-) But I suspect it’s not because Putins elections trolls forgot about Belfast for an afternoon :-)