I've got a GPS module hanging on the TTL UART wires of my Pi 3B. I don't access the module directly, but via `gpsd`. Now I've got the following issue: At every reboot, Raspbian (Buster) seems to reset the group and the privilege mask of the UART:

```
pi@autoradio:/import/valen/autoradio $ ls -al /dev/ttyS0
crw--w---- 1 root tty 4, 64 Sep 11 00:06 /dev/ttyS0

```

Consequence: `gpsd` can't access the module and quits:

```
pi@autoradio:/import/valen/autoradio $ sudo systemctl status gpsd
● gpsd.service - GPS (Global Positioning System) Daemon
   Loaded: loaded (/lib/systemd/system/gpsd.service; disabled; vendor preset: enabled)
   Active: active (running) since Sat 2021-09-11 00:05:55 CEST; 17min ago
 Main PID: 608 (gpsd)
    Tasks: 1 (limit: 2059)
   CGroup: /system.slice/gpsd.service
           └─608 /usr/sbin/gpsd /dev/ttyS0

Sep 11 00:05:55 autoradio systemd[1]: Starting GPS (Global Positioning System) Daemon...
Sep 11 00:05:55 autoradio systemd[1]: Started GPS (Global Positioning System) Daemon.
Sep 11 00:13:18 autoradio gpsd[608]: gpsd:ERROR: SER: device open of /dev/ttyS0 failed: Permission denied - retrying read-only
Sep 11 00:13:18 autoradio gpsd[608]: gpsd:ERROR: SER: read-only device open of /dev/ttyS0 failed: Permission denied
Sep 11 00:13:18 autoradio gpsd[608]: gpsd:ERROR: /dev/ttyS0: device activation failed.
Sep 11 00:13:18 autoradio gpsd[608]: gpsd:ERROR: /dev/ttyS0: activation failed, freeing device

```

As far as I can remember, I had a privilege structure like this before making a new SD card with a fresh Raspbian:

```
crw-rw---- 1 root dialout

```

Setting privileges by hand only works until the next shutdown. What's going on here? How can I tell Raspbian to get the hand off the privileges of `/dev/ttyS0`? Thank you.