[knot-dns-users] AXFR sender FINs 10% of the way through transfer

debian 12 # uname -a Linux rip.psg.com 6.1.0-18-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.76-1 (2024-02-01) x86_64 GNU/Linux # knotc --version knotc (Knot DNS), version 3.2.6 AXFR of a 750k zone from seattle to, lebanon, europe, iceland, southern africa, ...) fails over v5 and v6, i.e. somewhat larger rtt same AXFR seattle seattle or seattle to ashburn works v4 and v6. seattle to dallas v4 good, v6 fails, but it smells of an HE.net hop. when it fails, it is always within a hundred or so mytes of the same place, approximately 10% through the file. pcap of seattle->beirut at https://archive.psg.com/240323.beirut.pcap the last payload is in frame 217. at 219, seattle (b) sends a FIN/PSH/ACK. then at 251, after acking everything, beirut (nabil) FIN/ACKs seattle's FIN and we're dead. i am not positive this is the key question as my tcp fu is a bit rusty. but why did seattle send the FIN at 219, 10% through the file? randy