nRF9160 not connecting to LTE network

[tl300]

What can prevent an nrf9160 from connecting to an LTE network?  I have custom boards with 9160s as well as a DK with a variety of SIM cards.  Most days, I have no issues with connectivity and establish connections within seconds.  However, some days (like today), I can't get a connection at all, or it takes about 30 minutes.  When this happens, I usually switch to the DK and run the Cellular Monitor.  If I do get a connection, it almost always takes 25-30 minutes.  Further, if I close the Cell Monitor session and start again, a new connection takes another 25-30 minutes.  I live in a major US city, so connectivity should be fine.  I also get the same behavior across different SIM providers too. 

[tl300]

Sorry for the delay.  The issue was (is) the Reset Loop Restriction.  As noted in the docs, the %XFACTORYRESET=0 AT command resolves the issue for me (in development).  What is still confusing is how I have been able to hit this mechanism on different hardware running different software with different workflows.  As I wrote above, I have an nRF9160 DK provisioned with stock software (ATv2 and modem firmware 1.3.5).  I basically use it with Cell Monitor as a test tool.  When I run into connectivity issues with my custom devices, I break out the DK to check the network.  What is confusing is that when I hit the Reset Loop Restriction with my custom devices, I also seem to hit it with the DK.  I find this a bit strange, because, again, they are different hardware, software, and workflows.  My workflow with the DK is basically that from the Quick Start Guide.