BG95-M2 LTE-M / eMTC no UDP reception

I was able to monitor the following behavior:
After successful connection to PS network (timestamp 18170) the module disconnects from the network after ~8s (timestamp 26898). After another ~25s registration is denied (timestamp 50314), after another 2s it is registered successfully (timestamp 52347). Then sending and receiving data works without problems!

Any idea what causes this strange behaviour or how to solve it?

9816	command: AT+CGMM
9818	message: AT+CGMM
9818	message: BG95-M2
9819	message: OK
9819	LTE-M modem started successfully
9819	command: ATE0
9821	message: ATE0
9821	message: OK
9822	command: AT+QSCLK=0
9826	message: OK
9828	command: AT+QICFG="dataformat",1,1
9829	message: OK
9831	command: AT+QICFG="viewmode",1
9832	message: OK
9834	command: AT+QICFG="recvind",1
9835	message: OK
9972    command: AT+QCFG="iotopmode",0,1
9974    message: OK
14115   message: OK
18112   command: AT+QURCCFG="urcport","uart1"
18113   message: OK
18115   command: AT+CPIN?
18117   message: +CPIN: READY
18118   message: OK
18118   command: AT+CIMI
18121   message: <cimi>
18121   message: OK
18122   command: AT+CREG=0
18123   message: OK
18124   command: AT+CEREG=2
18126   message: OK
18126   command: AT+COPS=0
18134   message: OK
18135   command: AT+CPSMS=0
18137   message: OK
18139   command: AT+CEDRXS=0,5
18140   message: OK
18144   command: AT+QICSGP=1,1,"iot.1nce.net","","",1
18145   message: OK
18146   command: AT+CEREG?
18149   message: +CEREG: 2,5,"361A","1BE4E02",8
18150   message: OK
18151   command: AT+CREG?
18153   message: +CREG: 0,5
18153   message: OK
18154   command: AT+QNWINFO
18159   message: +QNWINFO: "eMTC","26201","LTE BAND 20",6400
18159   message: OK
18161   command: AT+QENG="servingcell"
18165   message: +QENG: "servingcell","SEARCH"
18166   message: OK
18167   command: AT+CEREG?
18170   message: +CEREG: 2,5,"361A","1BE4E02",8
18171   message: OK
18171   command: AT+CREG?
18173   message: +CREG: 0,5
18174   message: OK
18175   command: AT+QNWINFO
18180   message: +QNWINFO: "eMTC","26201","LTE BAND 20",6400
18180   message: OK
18182   command: AT+QENG="servingcell"
18186   message: +QENG: "servingcell","SEARCH"
18186   message: OK
26898   message: +CEREG: 2
50314   message: +CEREG: 3
52347   message: +CEREG: 5,"B0F8","C4B302",8
78186   command: AT+QIACT=1
78188   message: OK
78192   command: AT+QIOPEN=1,1,"UDP","10.66.33.117",5683,0,1
78193   message: OK
78197   command: AT+QISENDEX=1,<12 bytes of data>
78197   message: +QIOPEN: 1,0
78199   message: SEND OK
78842   message: +QIURC: "recv",1,4,70006C6C
88203   command: AT+QISENDEX=1,<12 bytes of data>
88205   message: SEND OK
88645   message: +QIURC: "recv",1,4,70006C6C