Update: I caught it with packets (headers only), same STC mobile SIM through an iPhone hotspot. The SIM is on AS39891 (STC mobile); AS39386 is its upstream, so my post above named the wrong one. On 2 Nov from 10:38 to 11:23 (UTC+3), about half of fresh IPv6 connections to iosapps.itunes.apple.com stalled, across 7 Apple edge sites at once. Then it stopped for all of them in the same minute. IPv4 never stalled. In each stall the TLS handshake completes. Then a RST arrives carrying the sequence number of the server's third data segment, which the client never acknowledged. iOS drops it as out of window and nothing else comes back. The App Clip install waits 60 s and fails. So it looks like a device on the IPv6 path between STC and Apple, not Apple's edge servers. I've reported it to STC and to Apple (FB25380604). Is there any way to get the App Clip install to retry once?