SIP trunk uregistered

I am running FreePBX v2.7.0.5 using two SIP trunks. Sometime today, primary trunk has become unregistered impeding inbound calls. I ran a scheduled backup last night. With no effect - the primary trunk remains unregistered - I have tried

  • server reboot
  • FreePBX restore from backup
  • various tips in another thread “Sipstation dropping registration”

I cannot get the primary trunk to register. Sipstation status fields show

  • Asterisk Reg. = Request Sent
  • Contact IP = BLANK
  • Network IP = Blank
  • SIP Ping = UNREACHABLE

Secondary trunk is registered.

Any help is greatly appreciated.

Thanks,
Tom Nall
Crystal Lake, IL