Group turned left, I went straight on

I see there are other historic similar issues; is it just a network connectivity issue? The other riders didn’t disappear, they were still visible making the turn. I exited, and fortunately could (late) rejoin, but it was annoying.

Activity ID: 811704718982014768
Mac OSX 11.3.1, latest client with updates (currently showing, 2 days later, 1.12.1 (67629)

Logfile shows (I think this is the most relevant, just before my “why didn’t I turn?” message):
[19:40:52] NETCLIENT:[INFO] UDP host^M
[19:40:52] NETCLIENT:[INFO] Connecting to UDP server…^M
[19:40:52] NETWORK:Stale data for player 719170^M
[19:40:52] NETWORK:206655977524/206655976778^M
[19:40:52] [FTMS] SIM (-0.1)^M
[19:40:53] NETCLIENT:[INFO] UDP host^M
[19:40:53] NETCLIENT:[INFO] Connecting to UDP server…^M
[19:40:53] [FTMS] SIM (-0.1)^M

[19:40:56] [FTMS] SIM (-0.0)^M
[19:40:56] FPS 37, 50907, 14390, -95165^M
[19:40:56] Starting critical power curve search job (233364111) mTimeStamp = 693.76141 m_lastSearchTime = 693.76141 calculating=false^M
[19:40:57] [FTMS] SIM (-0.0)^M

[19:41:04] [FTMS] SIM (0.8)^M
[19:41:04] FPS 34, 59101, 14392, -90266^M
[19:41:05] NETCLIENT:[INFO] World clock offset updated from -206182627289ms to -206182627292ms (-3ms)^M

Glitch in the Matrix?

1 Like

In theory, a stale UDP packet should simply be discarded. We see that Zwift found a stale (outdated, maybe delayed too much in the network) UDP data packet, probably dropped it, and moved to a different server. This happens quite often because UDP packets losses are not uncommon. Zwift can jump between servers at first signs of UDP delays, and usually it is not noticeable for us, Zwifters. If UDP packets do not come at all for about 4 seconds, other riders disappear, but you continue riding your route on your own.

I thought your route should be transmitted to client via TCP, not UDP? Could it be that you somehow did not join your group ride correctly? Or had a TCP issue in the very beginning, when ride has not even started yet?

P.S. I am not affiliated with Zwift, but I learned a few things about how Zwift communicates with servers while troubleshooting my firewall and studying firewall logs.