Ubuntu 18.04 LTS booting very slow after recent update

Question

Ubuntu 18.04 LTS is booting very slow after a recent update.
Below is systemd-analyze blame output:

6min 36.404s plymouth-quit-wait.service
    3min 36.636s snapd.seeded.service
         35.386s snapd.service
          6.287s NetworkManager-wait-online.service
          1.780s dev-sda5.device
          1.255s dev-loop4.device
          1.233s dev-loop3.device
          1.229s dev-loop0.device
          1.220s dev-loop2.device
          1.216s dev-loop7.device
          1.216s dev-loop5.device
          1.216s dev-loop1.device
          1.202s dev-loop8.device
          1.200s dev-loop6.device
          1.157s dev-loop9.device
           744ms fwupd.service
           650ms apparmor.service
           476ms systemd-rfkill.service
           402ms udisks2.service
           333ms systemd-journal-flush.service
           297ms networkd-dispatcher.service
           275ms plymouth-start.service
           255ms accounts-daemon.service

Kindly help

Thank you