A large TCP receive window does not remove the congestion window limit
TCP sender behaviour is constrained by both flow control and congestion control. Increasing one reported window does not prove that the other permits more outstanding data.
The journal
The viewing journal — page 61
Practical reading about streaming, devices and the decisions behind a better prepared setup.
A TCP retransmission timeout is not simply the latest round trip time
RFC 6298 calculates the retransmission timer using smoothed delay, delay variation and timer rules. A single ping value does not specify that timer.
A DNS ANY reply is not a complete list of a hostname records
Authoritative servers can return a minimal or selected response to ANY. Ask for the specific record types needed for the diagnostic question.
DNS over TCP is not only for transferring entire zones
DNS clients and servers need TCP support for ordinary resolution scenarios too. One successful small UDP lookup does not establish that the full DNS path works.
A changing IPv6 temporary address does not necessarily mean a new device
IPv6 temporary addressing can change an interface identifier over time. A log containing several addresses needs device and timing context before counting machines.
An IPv6 prefix can remain advertised without the sender being a default router
Router Advertisement information has separate roles and lifetimes. The Router Lifetime field applies to default router usefulness, not every option in the message.