The log using RAM:
prefix. I sent you the complete log, including custom DNS resolution, maybe it can give you information about the error.
[INFO][CELL]: AT TX (11): AT+QSECDEL=
[INFO][CELL]: AT TX (1): "
[INFO][CELL]: AT TX (16): RAM:cacert_0.pem
[INFO][CELL]: AT TX (1): "
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (9): <cr><ln>ERROR<cr><ln>
[DBG ][CELL]: AT error -3012
[INFO][CELL]: AT TX (13): AT+QSECWRITE=
[INFO][CELL]: AT TX (1): "
[INFO][CELL]: AT TX (16): RAM:cacert_0.pem
[INFO][CELL]: AT TX (1): "
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (4): 1545
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (11): <cr><ln>CONNECT<cr><ln>
[INFO][CELL]: AT TX (60): -----BEGIN CERTIFICATE-----<ln>MIIESTCCAzGgAwIBAgITBn+UV4WH6Kx3
...
[INFO][CELL]: AT RX (1): <cr>
[INFO][CELL]: AT RX (30): <ln>+QSECWRITE: 1545,5f05<cr><ln><cr><ln>OK<cr><ln>
[INFO][CELL]: AT TX (11): AT+QSSLCFG=
[INFO][CELL]: AT TX (1): "
[INFO][CELL]: AT TX (6): cacert
[INFO][CELL]: AT TX (1): "
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 0
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): "
[INFO][CELL]: AT TX (16): RAM:cacert_0.pem
[INFO][CELL]: AT TX (1): "
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (6): <cr><ln>OK<cr><ln>
[INFO][CELL]: AT TX (11): AT+CGPADDR=
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (11): <cr><ln>+CGPADDR:
[INFO][CELL]: AT RX (26): 1,"10.49.216.233"<cr><ln><cr><ln>OK<cr><ln>
# UDP DNS resolution using custom stack
[INFO][CELL]: AT TX (10): AT+QIOPEN=
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): "
[INFO][CELL]: AT TX (3): UDP
[INFO][CELL]: AT TX (1): "
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): "
[INFO][CELL]: AT TX (7): 8.8.8.8
[INFO][CELL]: AT TX (1): "
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (2): 53
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (6): <cr><ln>OK<cr><ln>
[INFO][CELL]: AT RX (11): <cr><ln>1, CONNEC
[INFO][CELL]: AT RX (6): T OK<cr><ln>
[INFO][CELL]: AT TX (10): AT+QISEND=
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (2): 29
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (4): <cr><ln>>
[INFO][CELL]: AT TX (29): <0>
[INFO][CELL]: AT RX (2): <cr><ln>
[INFO][CELL]: AT RX (9): SEND OK<cr><ln>
[INFO][CELL]: AT TX (8): AT+QIRD=
[INFO][CELL]: AT TX (1): 0
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (3): 256
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (6): <cr><ln>OK<cr><ln>
[INFO][CELL]: AT TX (8): AT+QIRD=
[INFO][CELL]: AT TX (1): 0
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (3): 256
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (6): <cr><ln>OK<cr><ln>
[INFO][CELL]: AT RX (17): <cr><ln>+QIRDI: 0,1,1<cr><ln>
[INFO][CELL]: AT TX (8): AT+QIRD=
[INFO][CELL]: AT TX (1): 0
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (3): 256
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (17): <cr><ln>+QIRD: 8.8.8.8:
[INFO][CELL]: AT RX (32): 53,UDP,157<cr><ln><0>
[INFO][CELL]: AT RX (6): <cr><ln>OK<cr><ln>
[INFO][CELL]: AT TX (8): AT+QIRD=
[INFO][CELL]: AT TX (1): 0
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (3): 256
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (6): <cr><ln>OK<cr><ln>
[INFO][CELL]: AT TX (8): AT+QIRD=
[INFO][CELL]: AT TX (1): 0
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (3): 256
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (6): <cr><ln>OK<cr><ln>
[INFO][CELL]: AT TX (8): AT+QIRD=
[INFO][CELL]: AT TX (1): 0
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (3): 256
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (6): <cr><ln>OK<cr><ln>
[INFO][CELL]: AT TX (8): AT+QIRD=
[INFO][CELL]: AT TX (1): 0
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (3): 256
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (6): <cr><ln>OK<cr><ln>
[INFO][CELL]: AT TX (8): AT+QIRD=
[INFO][CELL]: AT TX (1): 0
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (3): 256
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (6): <cr><ln>OK<cr><ln>
[INFO][CELL]: AT TX (8): AT+QIRD=
[INFO][CELL]: AT TX (1): 0
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (3): 256
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (6): <cr><ln>OK<cr><ln>
[INFO][CELL]: AT TX (8): AT+QIRD=
[INFO][CELL]: AT TX (1): 0
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (3): 256
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (6): <cr><ln>OK<cr><ln>
[INFO][CELL]: AT TX (8): AT+QIRD=
[INFO][CELL]: AT TX (1): 0
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (3): 256
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (6): <cr><ln>OK<cr><ln>
[INFO][CELL]: AT TX (8): AT+QIRD=
[INFO][CELL]: AT TX (1): 0
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (3): 256
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (6): <cr><ln>OK<cr><ln>
[INFO][CELL]: AT TX (8): AT+QIRD=
[INFO][CELL]: AT TX (1): 0
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (3): 256
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (6): <cr><ln>OK<cr><ln>
[INFO][CELL]: AT TX (8): AT+QIRD=
[INFO][CELL]: AT TX (1): 0
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (3): 256
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (6): <cr><ln>OK<cr><ln>
[INFO][CELL]: AT TX (8): AT+QIRD=
[INFO][CELL]: AT TX (1): 0
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (3): 256
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (6): <cr><ln>OK<cr><ln>
[INFO][CELL]: AT TX (8): AT+QIRD=
[INFO][CELL]: AT TX (1): 0
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (3): 256
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (6): <cr><ln>OK<cr><ln>
[INFO][CELL]: AT TX (8): AT+QIRD=
[INFO][CELL]: AT TX (1): 0
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (3): 256
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (6): <cr><ln>OK<cr><ln>
[INFO][CELL]: AT TX (8): AT+QIRD=
[INFO][CELL]: AT TX (1): 0
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (3): 256
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (6): <cr><ln>OK<cr><ln>
[INFO][CELL]: AT TX (8): AT+QIRD=
[INFO][CELL]: AT TX (1): 0
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (3): 256
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (5): <cr><ln>OK<cr>
[INFO][CELL]: AT RX (1): <ln>
[INFO][CELL]: AT TX (8): AT+QIRD=
[INFO][CELL]: AT TX (1): 0
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (3): 256
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (6): <cr><ln>OK<cr><ln>
[INFO][CELL]: AT TX (8): AT+QIRD=
[INFO][CELL]: AT TX (1): 0
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (3): 256
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (6): <cr><ln>OK<cr><ln>
# Socket 1 recv 157 bytes from 8.8.8.8 port 53
[INFO][CELL]: AT TX (11): AT+QICLOSE=
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (12): <cr><ln>1, CLOSE O
[INFO][CELL]: AT RX (3): K<cr><ln>
# Resolution OK, starting TLS
[INFO][CELL]: AT TX (22): AT+QSSLCFG="seclevel",
[INFO][CELL]: AT TX (1): 0
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 1
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (6): <cr><ln>OK<cr><ln>
[INFO][CELL]: AT TX (24): AT+QSSLCFG="sslversion",
[INFO][CELL]: AT TX (1): 0
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 4
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (6): <cr><ln>OK<cr><ln>
[INFO][CELL]: AT TX (25): AT+QSSLCFG="ciphersuite",
[INFO][CELL]: AT TX (1): 0
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (8): "0XFFFF"
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (6): <cr><ln>OK<cr><ln>
[INFO][CELL]: AT TX (12): AT+QSSLOPEN=
[INFO][CELL]: AT TX (1): 0
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 0
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): "
[INFO][CELL]: AT TX (12): 54.91.118.50
[INFO][CELL]: AT TX (1): "
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (3): 443
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 0
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (2): 90
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (6): <cr><ln>OK<cr><ln>
[INFO][CELL]: AT TX (13): AT+QSSLCLOSE=
[INFO][CELL]: AT TX (1): 0
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (9): <cr><ln>ERROR<cr><ln>
[INFO][CELL]: AT TX (12): AT+QSSLOPEN=
[INFO][CELL]: AT TX (1): 0
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 0
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): "
[INFO][CELL]: AT TX (12): 54.91.118.50
[INFO][CELL]: AT TX (1): "
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (3): 443
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (1): 0
[INFO][CELL]: AT TX (1): ,
[INFO][CELL]: AT TX (2): 90
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (6): <cr><ln>OK<cr><ln>
[INFO][CELL]: AT TX (13): AT+QSSLCLOSE=
[INFO][CELL]: AT TX (1): 0
[INFO][CELL]: AT TX (1): <cr>
[INFO][CELL]: AT RX (9): <cr><ln>ERROR<cr><ln>