I think you're likely right, there. It's a TP-Link router which I've never had a problem with before, but I think I came across a few posts on here that name TP-Link and strange problems.
Weirdly, it didn't affect any other devices on the network, including the laptop I posted here from (which is also on the 2.4 gig radio). The "bad reply format version" message confused me, too (although that doesn't take much these days
☺ ).