Reboot Modem, than when Modem is done rebooting, reboot Ooma, than reboot router.
Second if First didn't work:
Access Ooma Setup pages by typing in http://172.27.35.1 in your comptuter brower's window that is connected to your Ooma device's Home port with a network cable. Click on "Internet Settings", go to Connection type, select the down arrow and select "Automatic, if not already selected. Next go down to "INTERNET port MAC Address:" and click "Use Built-In" button. Click on update button below. Reboot your Ooma device.
Third if First and Second didn't work, contact Ooma Customer support. Sometimes they can restart your VPN tunnel from their end.
Phone: 1-888-711-OOMA (6662)
Monday-Friday 7am-7pm PST
Saturday-Sunday 8am-5pm PST