I was just in DC with my FP2 the other day and couldn’t get coverage in the tunnels either (my last phone, LG v10 did work in tunnels) and have AT&T. I also didn’t have data coverage above ground, I was around the SCOTUS building, IDK if because the buildings are so big around the area they put repeaters around, that would make sense to me just a guess. Do you get fine coverage in DC above ground?