nRF9160 custom board and nRFcloud


I'm trying to test a custom board on nRFcloud with v1.1.0 tagged asset tracker firmware and v1.1.0 modem firmware. Is this possible?    

I can generate and provision cloud certificates as described in the guide:

I'm using a 5 character prefix + IMEI as the IMEI, and can get the device to add to my account. However, LED4 never lights and the connection keeps getting dropped with a POLLHUP and the board reboots. The cycle repeats. Here's one example from a log:

2019-12-04T23:08:42.497Z DEBUG modem << Connecting to LTE network. This may take several minutes.\x0D
2019-12-04T23:08:42.530Z DEBUG modem << [00:00:00.542,633] \x1B[0m<dbg> lte_lc.w_lte_lc_connect: Network mode: AT%XSYSTEMMODE=1,0,1,0\x1B[0m\x0D\x0A
2019-12-04T23:08:44.297Z DEBUG modem << +CEREG: 2,"C00C","02EE9002",7,0,0,"11100000","11100000"\x0D\x0A
2019-12-04T23:08:44.326Z DEBUG modem << [00:00:02.339,080] \x1B[0m<dbg> lte_lc.parse_nw_reg_status: Network registration status: 2\x1B[0m\x0D\x0A
2019-12-04T23:08:45.620Z DEBUG modem << +CEREG: 5,"C00C","02EE9002",7,,,"11100000","11100000"\x0D
2019-12-04T23:08:45.645Z DEBUG modem << [00:00:03.661,926] \x1B[0m<dbg> lte_lc.parse_nw_reg_status: Network registration status: 5\x1B[0m\x0D\x0A
2019-12-04T23:08:45.646Z DEBUG modem << Connected to LTE network\x0D\x0A
2019-12-04T23:08:46.051Z DEBUG modem << [00:00:04.085,296] \x1B[0m<dbg> nrf_cloud_transport.nct_connect: IPv4 Address 0xa599ca34\x1B[0m\x0D
2019-12-04T23:08:52.202Z DEBUG modem << Socket error: POLLHUP\x0D\x0A
2019-12-04T23:08:52.204Z DEBUG modem << LTE link disconnect\x0D
2019-12-04T23:08:52.288Z DEBUG modem << +CEREG: 0,"C00C","02EE9002",7,0,0,"11100000","11100000"\x0D\x0A
2019-12-04T23:08:53.887Z DEBUG modem << Shutdown modem\x0D\x0A
2019-12-04T23:08:55.337Z DEBUG modem << ***** Booting Zephyr OS build v2.0.99-ncs1 *****\x0D

The same SIM and firmware work on a 0.8.5 nRF9160-DK -- it connects and sends data to nRFcloud. I get the same results (working with DK, POLLHUP on custom board) with SIMs from 3 different vendors. These three SIMs all connect on the custom board with at_client firmware.

Here's a full log: nRFcloud disconnect AssetTracker POLLHUP.txt