I did the factory reset and then reconfigured for 3G/4G access.
This is the D-Link Pocket Cloud Router, H/W version A2.
The loaded firmware is 20130708_D-Link_DIR-506L_V2.15b02.bin from DIR-506L_fw_revA2_2-15B02_all_en_20130819.zip.
The signal strength looks good.
This is my 4G card: http://www.pantechusa.com/modems/fourg-usb-modem/
Here is part of the log:
Dec 31 16:59:58 kernel: klogd started: BusyBox v1.3.2 (2013-01-21 09:46:34 CST)
Dec 31 17:00:00 BEID: BEID STATUS : 0 , STATUS OK!
Dec 31 17:00:00 commander: Ethernet port configuration: Configured as WAN
Dec 31 17:00:02 syslog: Failure parsing line 12 of /etc/udhcpd.conf
Dec 31 17:00:02 syslog: server_config.pool_check = 1
Dec 31 17:00:02 syslog: start = 192.168.0, end = 192.168.0, lan_ip = 192.168.0, interface=br0, ifindex=0
Dec 31 17:00:02 udhcpd[1127]: udhcpd (v0.9.9-pre) started
Dec 31 17:00:07 commander: Init NAT Server ...
Dec 31 17:00:12 syslog: ===============================================
Dec 31 17:00:12 syslog: family_member = 6E21
<redacted>
Dec 31 17:00:12 syslog: ===============================================
Dec 31 17:00:13 iChecksum:: ===============================================
Dec 31 17:00:13 iChecksum:: family_member = 6E21
<redacted>
Dec 31 17:00:13 iChecksum:: ===============================================
Dec 31 17:00:15 init: Starting pid 2307, console /dev/ttyS1: '/bin/ash'
Dec 31 17:00:16 commander: STOP WANTYPE 3G
Dec 31 17:00:17 commander: Enter Power Saving Mode
Dec 31 17:00:17 commander: Start SharePort
Dec 31 17:00:30 commander: AutoSel Ethernet Port: Configured as LAN
Dec 31 17:02:48 commander: Exit Power Saving Mode
Dec 31 17:04:50 O3G/hotplug: 3G modem VendorID=106c ProductID=3718
Dec 31 17:05:08 O3G/hotplug: check setting!!
Dec 31 17:05:27 O3G/auto_apn: Cannot get mcc .NO support autoapn!!
Dec 31 17:05:27 <redacted, just in case>
Dec 31 17:05:30 commander: START WANTYPE 3G
Dec 31 17:05:40 pppd[17523]: pppd 2.4.4 started by root, uid 0
Dec 31 17:05:40 chat[17528]: abort on (BUSY)
Dec 31 17:05:40 chat[17528]: abort on (NO CARRIER)
Dec 31 17:05:40 chat[17528]: abort on (ERROR)
Dec 31 17:05:40 chat[17528]: timeout set to 10 seconds
Dec 31 17:05:40 chat[17528]: send (AT^M)
Dec 31 17:05:40 chat[17528]: expect (OK)
Dec 31 17:05:40 chat[17528]: ^M
Dec 31 17:05:40 chat[17528]: OK
Dec 31 17:05:40 chat[17528]: -- got it
Dec 31 17:05:40 chat[17528]: send (ATD*99#^M)
Dec 31 17:05:40 chat[17528]: expect (CONNECT)
Dec 31 17:05:40 chat[17528]: ^M
Dec 31 17:05:40 chat[17528]: ^M
Dec 31 17:05:40 chat[17528]: NO CARRIER
Dec 31 17:05:40 chat[17528]: -- failed
Dec 31 17:05:40 chat[17528]: Failed (NO CARRIER)
Dec 31 17:05:40 pppd[17523]: Connect script failed
Dec 31 17:05:40 pppd[17523]: Exit.
Dec 31 17:06:26 commander: STOP WANTYPE 3G
Dec 31 17:06:27 commander: START WANTYPE 3G
Dec 31 17:06:36 pppd[20761]: pppd 2.4.4 started by root, uid 0
Dec 31 17:06:36 chat[20765]: abort on (BUSY)
Dec 31 17:06:36 chat[20765]: abort on (NO CARRIER)
Dec 31 17:06:36 chat[20765]: abort on (ERROR)
Dec 31 17:06:36 chat[20765]: timeout set to 10 seconds
Dec 31 17:06:36 chat[20765]: send (AT^M)
Dec 31 17:06:36 chat[20765]: expect (OK)
Dec 31 17:06:36 chat[20765]: ^M
Dec 31 17:06:36 chat[20765]: OK
Dec 31 17:06:36 chat[20765]: -- got it
Dec 31 17:06:36 chat[20765]: send (ATD*99#^M)
Dec 31 17:06:36 chat[20765]: expect (CONNECT)
Dec 31 17:06:36 chat[20765]: ^M
Dec 31 17:06:36 chat[20765]: ^M
Dec 31 17:06:36 chat[20765]: NO CARRIER
Dec 31 17:06:36 chat[20765]: -- failed
Dec 31 17:06:36 chat[20765]: Failed (NO CARRIER)
Dec 31 17:06:36 pppd[20761]: Connect script failed
Dec 31 17:06:36 pppd[20761]: Exit.
Dec 31 17:07:22 commander: STOP WANTYPE 3G
Dec 31 17:07:23 commander: START WANTYPE 3G
Dec 31 17:07:32 pppd[24039]: pppd 2.4.4 started by root, uid 0
Dec 31 17:07:32 chat[24043]: abort on (BUSY)
Dec 31 17:07:32 chat[24043]: abort on (NO CARRIER)
Dec 31 17:07:32 chat[24043]: abort on (ERROR)
Dec 31 17:07:32 chat[24043]: timeout set to 10 seconds
Dec 31 17:07:32 chat[24043]: send (AT^M)
Dec 31 17:07:32 chat[24043]: expect (OK)
Dec 31 17:07:32 chat[24043]: ^M
Dec 31 17:07:32 chat[24043]: OK
Dec 31 17:07:32 chat[24043]: -- got it
Dec 31 17:07:33 chat[24043]: send (ATD*99#^M)
Dec 31 17:07:33 chat[24043]: expect (CONNECT)
Dec 31 17:07:33 chat[24043]: ^M
Dec 31 17:07:33 chat[24043]: ^M
Dec 31 17:07:33 chat[24043]: NO CARRIER
Dec 31 17:07:33 chat[24043]: -- failed
Dec 31 17:07:33 chat[24043]: Failed (NO CARRIER)
Dec 31 17:07:33 pppd[24039]: Connect script failed
Dec 31 17:07:33 pppd[24039]: Exit.
Dec 31 17:08:18 commander: STOP WANTYPE 3G
Dec 31 17:08:19 commander: START WANTYPE 3G
Dec 31 17:08:29 pppd[27326]: pppd 2.4.4 started by root, uid 0
Dec 31 17:08:29 chat[27332]: abort on (BUSY)
Dec 31 17:08:29 chat[27332]: abort on (NO CARRIER)
Dec 31 17:08:29 chat[27332]: abort on (ERROR)
Dec 31 17:08:29 chat[27332]: timeout set to 10 seconds
Dec 31 17:08:29 chat[27332]: send (AT^M)
Dec 31 17:08:29 chat[27332]: expect (OK)
Dec 31 17:08:29 chat[27332]: ^M
Dec 31 17:08:29 chat[27332]: OK
Dec 31 17:08:29 chat[27332]: -- got it
Dec 31 17:08:29 chat[27332]: send (ATD*99#^M)
Dec 31 17:08:29 chat[27332]: expect (CONNECT)
Dec 31 17:08:29 chat[27332]: ^M
Dec 31 17:08:29 chat[27332]: ^M
Dec 31 17:08:29 chat[27332]: NO CARRIER
Dec 31 17:08:29 chat[27332]: -- failed
Dec 31 17:08:29 chat[27332]: Failed (NO CARRIER)
Dec 31 17:08:29 pppd[27326]: Connect script failed
Dec 31 17:08:29 pppd[27326]: Exit.