Cannot dial out - all circuits are busy

FreePBX 13.0.163
Asterisk 13.10.0

Suddenly I cannot make any outbound calls on any extension. A log snippet from the attempted outbound call through Flowroute:

[2016-08-09 14:34:42] WARNING[21362][C-00000006]: app_dial.c:2432 dial_exec_full: Unable to create channel of type ‘SIP’ (cause 20 - Subscriber absent)
== Everyone is busy/congested at this time (1:0/0/1)
– Executing [[email protected]:24] NoOp(“SIP/300-00000006”, “Dial failed for some reason with DIALSTATUS = CHANUNAVAIL and HANGUPCAUSE = 20”) in new stack

I attempted to get Module updates, but received the following message:

Warning: Cannot connect to online repository(s) (, Online modules are not available.

Any ideas on what might correct this?

I had been fooling around with System Admin module. I looked at DNS settings and saw a note there which said should be the first entry, so I added it, or so I thought.

I turns out it was the only entry. That’s why the pbx could not get out.