NR5101 randomly loses network connection (log says: QMI error)

After having worked well for about a year, my NR5101 stopped working correctly.

It disconnects to the network and stays disconnected. It also doesn't try to reconnect anymore. This happens about 6-9 times per week. The log file gives out QMI errors and the system freezes. Only a full reboot does help.

Below is the log file right before it happens. You can see:

• 06:56:40 - Connection is still up
• 06.56:49 - LTE connection is lost
• 06:56:51 - Tries to search
• 06:56:54 - modem is ready to re-connect
• 06:56:57 - This is when the Qualcomm MSM interface error happens and the whole system effectively freezes.

Nov 22 06:56:40 user.notice RILCMD: Current Tech = NR-NSA EN-DC, PCID:483, RFCN:100, DL_BandWidth:20MHz, UL_BandWidth:20MHz, RSSI:-60dBm, RSRQ:-8dB, RSRP:-88dBm
Nov 22 06:56:49 user.notice RILCMD: set_LTE_connection_status: Down
Nov 22 06:56:51 user.notice RILCMD: CREG_INTERNAL_NOT_REG_DO_SEARCH detected
Nov 22 06:56:52 user.notice zcmdModuleCfg: System: Wan interface Cellular WAN 1 connection lost
Nov 22 06:56:54 user.notice RILCMD: quectel_rg500q_ready() Next to RS_ATTACH state
Nov 22 06:56:57 user.notice RILCMD: Reset LTE module because of QMI error.

What I tried: I used the same SIM card in another device without any problems for many days, so I don't believe it's the SIM card. I also tried turning of auto band selection and stayed on particular bands to avoid switching - without any difference to the behaviour.

What can I do? I starts to get worse, too. It happened about 4 times a day recently and during things like video conferences, which is bad. Some research told me, that this might even be a hardware fault.