[Solved] OPNsense 20.1.6-amd64: Unable to connect after upgrade

[decalpha]

Hi,
  I have been using OPNsense since last couple of years.
  Thanks for this wonderful piece of software.

  Was earlier on 20.14, and decided to skip 20.1.5 and upgraded today to 20.1.6.
  After reboot, I lost internet connectivity.
 
  Network topology: [computers] --- [switch] --- [opnsense(PPPoE)] --- [Modem]
 
  I tried restoring last known good configuration dated 10th April 2020 after factory reset.
  This again worked for some time probably 10 minutes before I realised that I have lost connectivity.
  Next thing I tried is to take a diff between last know good config and one after upgrade.
  Do still see following differences:
  Working:     
     <Netflow version="1.0.0">
      <capture>
        <interfaces/>
        <egress_only>wan</egress_only>
        <version>v9</version>
        <targets/>
      </capture>
      <collect>
        <enable>0</enable>
      </collect>
    </Netflow>
  20.1.6:
      <Netflow version="1.0.1">
      <capture>
        <interfaces/>
        <egress_only>wan</egress_only>
        <version>v9</version>
        <targets/>
      </capture>
      <collect>
        <enable>0</enable>
      </collect>
      <activeTimeout>1800</activeTimeout>
      <inactiveTimeout>15</inactiveTimeout>
    </Netflow>
  </OPNsense>

  Please let me know, not sure that the above difference could be the cause of this.
  Should I install OPNsense 20.1.4 again from scratch and restore the configuration file ?

  Last but not the least, check for updates from within the GUI doesn't throw connectivity error.
  Though Audit Now, throws No address record.
  For some reason, that's the only component capable of connecting to the internet.
 
  Appreciate pointers to resolve this.

Regards,
Prashant

Update: Disabling DNSSEC on Pi-Hole solved the issue, this was working prior to update.