Without logs we won't be able to help you.
Show the correct locations:
3e52505636333233392b333735353339352d313230383332323231353932373730323b49443d373131323b2a37323c
2019-04-24 17:33:42 INFO: [c7041e7b: 5031 > x.x.x.x] HEX: 37313132
2019-04-24 17:33:42 INFO: [c7041e7b] id: 7112, time: 2019-04-24 17:33:59, lat: 37.55395, lon: -120.83222, speed: 138.2, course: 277.0
2019-04-24 17:33:44 INFO: [c7041e7b: 5031 < x.x.x.x] HEX: 3e52505636333234312b333735353431322d313230383333383031353832373830323b49443d373131323b2a37323c
2019-04-24 17:33:44 INFO: [c7041e7b: 5031 > x.x.x.x] HEX: 37313132
2019-04-24 17:33:44 INFO: [c7041e7b] id: 7112, time: 2019-04-24 17:34:01, lat: 37.55412, lon: -120.83380, speed: 137.3, course: 278.0
Recording all zeros and showing in the middle of the sea:
3e52505636373933312b333736343737382d313230393339343231373431333130303b49443d373131323b2a37303c
2019-04-24 18:51:54 INFO: [c7041e7b: 5031 > x.x.x.x] HEX: 37313132
2019-04-24 18:51:54 INFO: [c7041e7b] id: 7112, time: 2019-04-24 18:52:11, lat: 37.64778, lon: -120.93942, speed: 151.2, course: 131.0
2019-04-24 18:51:56 INFO: [c7041e7b: 5031 < x.x.x.x] HEX: 3e52505636373933332b333736343636352d313230393338373931363931333330303b49443d373131323b2a37383c
2019-04-24 18:51:56 INFO: [c7041e7b: 5031 > x.x.x.x] HEX: 37313132
2019-04-24 18:51:56 INFO: [c7041e7b] id: 7112, time: 2019-04-24 18:52:13, lat: 37.64665, lon: -120.93879, speed: 146.9, course: 133.0
Those are clearly not zeroes.
Yes.. those are not... but the web interface is showing all zeros and the device in the middle of the ocean.
Web shows green and
Time
2019-04-23 17:00:00
Latitude
0.000000°
Longitude
0.000000°
...
Please read documentation:
https://www.traccar.org/forums/topic/0-longitude-and-0-latitude/
Everything is working fine and dandy... tracking, recording data... then all of the sudden location shows at 0.000000° When tracking first starts everything is fine, usually after a "while" it starts showing 0.000000° and the device in the middle of the ocean.
Looked at the logs and the data checks out and showing good Lat Lon speed and course in there.