Been using syncthing for a little bit, and I just recently received a warning in the webgui this morning - 3 different time stamps, a few minutes apart with the message:
“Detected a flip-flopping listener”
A google search resulted in only 2 useful results: a reddit post a year ago where someone was looking for what this meant and in the reddit thread, they linked to the github repo where that string exists. The second link was to the github repo where that string exists.
There doesn’t appear to be any documentation or explanation for what this means and what corrective action should be taken. Any ideas?
[BPGAV] 2023/05/01 02:57:51 WARNING: Detected a flip-flopping listener
[BPGAV] 2023/05/01 02:58:20 INFO: Relay listener (dynamic+https://relays.syncthing.net/endpoint) shutting down
[BPGAV] 2023/05/01 02:58:20 INFO: listenerSupervisor@dynamic+https://relays.syncthing.net/endpoint: service dynamic+https://relays.syncthing.net/endpoint failed: could not find a connectable relay
[BPGAV] 2023/05/01 02:58:20 INFO: Relay listener (dynamic+https://relays.syncthing.net/endpoint) starting
[BPGAV] 2023/05/01 02:58:21 WARNING: Detected a flip-flopping listener
[BPGAV] 2023/05/01 02:58:50 INFO: Relay listener (dynamic+https://relays.syncthing.net/endpoint) shutting down
[BPGAV] 2023/05/01 02:58:50 INFO: listenerSupervisor@dynamic+https://relays.syncthing.net/endpoint: service dynamic+https://relays.syncthing.net/endpoint failed: Get "https://relays.syncthing.net/endpoint": dial tcp: lookup relays.syncthing.net: no such host
[BPGAV] 2023/05/01 02:58:50 INFO: Relay listener (dynamic+https://relays.syncthing.net/endpoint) starting
[BPGAV] 2023/05/01 02:59:20 INFO: Relay listener (dynamic+https://relays.syncthing.net/endpoint) shutting down
[BPGAV] 2023/05/01 02:59:20 INFO: listenerSupervisor@dynamic+https://relays.syncthing.net/endpoint: service dynamic+https://relays.syncthing.net/endpoint failed: Get "https://relays.syncthing.net/endpoint": dial tcp: lookup relays.syncthing.net: i/o timeout
[BPGAV] 2023/05/01 02:59:20 INFO: Relay listener (dynamic+https://relays.syncthing.net/endpoint) starting
[BPGAV] 2023/05/01 03:00:15 INFO: Relay listener (dynamic+https://relays.syncthing.net/endpoint) shutting down
[BPGAV] 2023/05/01 03:00:15 INFO: listenerSupervisor@dynamic+https://relays.syncthing.net/endpoint: service dynamic+https://relays.syncthing.net/endpoint failed: Get "https://relays.syncthing.net/endpoint": dial tcp: lookup relays.syncthing.net: no such host
[BPGAV] 2023/05/01 03:00:15 INFO: Relay listener (dynamic+https://relays.syncthing.net/endpoint) starting
[BPGAV] 2023/05/01 03:37:03 INFO: Relay listener (dynamic+https://relays.syncthing.net/endpoint) shutting down
[BPGAV] 2023/05/01 03:37:03 INFO: listenerSupervisor@dynamic+https://relays.syncthing.net/endpoint: service dynamic+https://relays.syncthing.net/endpoint failed: Get "https://relays.syncthing.net/endpoint": dial tcp: lookup relays.syncthing.net: i/o timeout
[BPGAV] 2023/05/01 03:37:03 INFO: Relay listener (dynamic+https://relays.syncthing.net/endpoint) starting
[BPGAV] 2023/05/01 03:37:03 INFO: Relay listener (dynamic+https://relays.syncthing.net/endpoint) shutting down
[BPGAV] 2023/05/01 03:37:03 INFO: listenerSupervisor@dynamic+https://relays.syncthing.net/endpoint: service dynamic+https://relays.syncthing.net/endpoint failed: Get "https://relays.syncthing.net/endpoint": dial tcp 143.244.196.6:443: connectex: A socket operation was attempted to an unreachable network.
[BPGAV] 2023/05/01 03:37:03 WARNING: Detected a flip-flopping listener
[BPGAV] 2023/05/01 03:38:42 INFO: Relay listener (dynamic+https://relays.syncthing.net/endpoint) starting
[BPGAV] 2023/05/01 03:55:10 INFO: Relay listener (dynamic+https://relays.syncthing.net/endpoint) shutting down
[BPGAV] 2023/05/01 03:55:10 INFO: listenerSupervisor@dynamic+https://relays.syncthing.net/endpoint: service dynamic+https://relays.syncthing.net/endpoint failed: could not find a connectable relay
Not sure if it’s helpful at all, or if there’s somewhere else I should be looking? This warning only occurred on my Windows 11 machine - I’m syncing various folders between a Windows 10 machine and an Android phone.
The gist of it is that syncthing can’t talk to relays.syncthing.net for various odd reasons. Proxies, antivirus, firewalls, etc all feel like likely culprits. Assuming this machine has working internet access at all.
Hmm…that’s weird…Yes, this machine has full working internet access. I was able to ping that address no problem:
Ping results
ping relays.syncthing.net
Pinging ams3-k8s.syncthing.net [143.244.196.6] with 32 bytes of data:
Reply from 143.244.196.6: bytes=32 time=137ms TTL=33
Reply from 143.244.196.6: bytes=32 time=140ms TTL=33
Reply from 143.244.196.6: bytes=32 time=136ms TTL=33
Reply from 143.244.196.6: bytes=32 time=142ms TTL=33
Ping statistics for 143.244.196.6:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 136ms, Maximum = 142ms, Average = 138ms
As well as a traceroute:
Traceroute results
tracert relays.syncthing.net
Tracing route to ams3-k8s.syncthing.net [143.244.196.6]
over a maximum of 30 hops:
1 4 ms 3 ms 3 ms tplinkwifi.net [10.0.0.1]
2 13 ms 12 ms 10 ms 96.120.97.249
3 13 ms 10 ms 10 ms 96.108.40.189
4 11 ms 11 ms 12 ms be-310-arsc1.northdade.fl.pompano.comcast.net [68.86.165.141]
5 13 ms 11 ms 14 ms be-33811-cs01.miami.fl.ibone.comcast.net [96.110.45.65]
6 16 ms 12 ms 13 ms be-3111-pe11.nota.fl.ibone.comcast.net [96.110.33.146]
7 12 ms 11 ms 13 ms 50.248.119.186
8 36 ms 36 ms 36 ms rest-bb1-link.ip.twelve99.net [62.115.119.230]
9 45 ms 42 ms 45 ms nyk-bb1-link.ip.twelve99.net [62.115.141.245]
10 127 ms 129 ms 129 ms nyk-b1-link.ip.twelve99.net [62.115.135.131]
11 127 ms 133 ms 129 ms nyk-bb2-link.ip.twelve99.net [62.115.135.132]
12 126 ms 129 ms 128 ms ash-bb2-link.ip.twelve99.net [62.115.136.201]
13 127 ms 126 ms 128 ms prs-bb1-link.ip.twelve99.net [62.115.112.243]
14 127 ms 126 ms 128 ms ldn-bb1-link.ip.twelve99.net [62.115.135.24]
15 * * * Request timed out.
16 131 ms 160 ms 130 ms slou-b2-link.ip.twelve99.net [62.115.112.63]
17 216 ms 271 ms 147 ms digitalocean-ic-306495.ip.twelve99-cust.net [62.115.44.254]
18 * * * Request timed out.
19 * * * Request timed out.
20 * * * Request timed out.
21 * * * Request timed out.
22 * * * Request timed out.
23 136 ms 134 ms 139 ms 143.244.196.6
Trace complete.
There does appear to be some timeouts on the route over to relays.syncthing.net, but it eventually gets there. Perhaps it was just a one-time glitch with the flip-flopping warning…just didn’t seem to make any sense…if syncthing couldn’t connect to a relay, that warning doesn’t really seem to indicate that the issue was a connectivity one…not really sure what flip-flopping means in the context of a listener…