The route marker took a free TCP port and bound UDP on the same number, which
fails whenever that UDP port is in use or reserved (Windows excludes port ranges
per protocol), so the TUIC routing tests failed at random on such hosts.
TUIC traffic reached Xray through a loopback SOCKS relay that took no login,
so Xray never learned which client a connection belonged to and user routing
rules never matched TUIC (#6874). The relay now carries one account per client
email, so per-user rules match on TCP and both UDP modes; admission stays with
the native TUIC server.
Adding, removing or renaming a TUIC client swaps only that inbound's relay
instead of restarting Xray: new sessions wait behind a bounded gate while live
streams and UDP associations continue, accounts are verified after the swap and
rolled back on failure, one failing relay no longer strands the others or blocks
unrelated live changes, and emails over SOCKS5's 255-byte limit are excluded
with a warning.