There might many reasons why you are not able to get signal.
1) Make sure you mounted the antennas correctly and have functioning antennas.
2) Make sure to place the antenna outside, otherwise the router will not likely obtain a GPS fix.
3) If this happened exactly after the upgrade, try reloading the latest firmware but don't forget to unclick 'keep all settings' this time.
4) Try downgrading.
If nothing solves the issue, send me your Troubleshoot file via pm.