After I had to force a shutdown, because lubuntu was not responding anymore it hangs while starting, here is what I found in the boot.log Thanks a lot !
[[0;32m OK [0m] Started [0;1;39mShow Plymouth Boot Screen[0m.
[[0;32m OK [0m] Started [0;1;39mFlush Journal to Persistent Storage[0m.
Starting [0;1;39mCreate Volatile Files and Directories[0m...
[[0;32m OK [0m] Started [0;1;39mCreate Volatile Files and Directories[0m.
[[0;32m OK [0m] Started [0;1;39mEntropy daemon using the HAVEGE algorithm[0m.
Starting [0;1;39mUpdate UTMP about System Boot/Shutdown[0m...
Starting [0;1;39mNetwork Name Resolution[0m...
Starting [0;1;39mNetwork Time Synchronization[0m...
[[0;32m OK [0m] Started [0;1;39mUpdate UTMP about System Boot/Shutdown[0m.
[[0;32m OK [0m] Started [0;1;39mNetwork Time Synchronization[0m.
[[0;32m OK [0m] Reached target [0;1;39mSystem Time Set[0m.
[[0;32m OK [0m] Reached target [0;1;39mSystem Time Synchronized[0m.
[[0;32m OK [0m] Reached target [0;1;39mSystem Initialization[0m.
[[0;32m OK [0m] Started [0;1;39mDaily man-db regeneration[0m.
[[0;32m OK [0m] Listening on [0;1;39mAvahi mDNS/DNS-SD Stack Activation Socket[0m.
[[0;32m OK [0m] Started [0;1;39mCUPS Scheduler[0m.
[[0;32m OK [0m] Started [0;1;39mPeriodic ext4 Online Metadata Check for All Filesystems[0m.
[[0;32m OK [0m] Started [0;1;39mACPI Events Check[0m.
[[0;32m OK [0m] Started [0;1;39mTrigger anacron every hour[0m.
[[0;32m OK [0m] Listening on [0;1;39mACPID Listen Socket[0m.
[[0;32m OK [0m] Started [0;1;39mMessage of the Day[0m.
[[0;32m OK [0m] Listening on [0;1;39mCUPS Scheduler[0m.
[[0;32m OK [0m] Started [0;1;39mDaily Cleanup of Temporary Directories[0m.
[[0;32m OK [0m] Listening on [0;1;39mUUID daemon activation socket[0m.
[[0;32m OK [0m] Started [0;1;39mDiscard unused blocks once a week[0m.
[[0;32m OK [0m] Started [0;1;39mDaily rotation of log files[0m.
[[0;32m OK [0m] Started [0;1;39mDaily apt download activities[0m.
Starting [0;1;39mSocket activation for snappy daemon[0m.
[[0;32m OK [0m] Listening on [0;1;39mD-Bus System Message Bus Socket[0m.
[[0;32m OK [0m] Started [0;1;39mDaily apt upgrade and clean activities[0m.
[[0;32m OK [0m] Reached target [0;1;39mTimers[0m.
[[0;32m OK [0m] Reached target [0;1;39mPaths[0m.
[[0;32m OK [0m] Listening on [0;1;39mSocket activation for snappy daemon[0m.
[[0;32m OK [0m] Reached target [0;1;39mSockets[0m.
[[0;32m OK [0m] Reached target [0;1;39mBasic System[0m.
Starting [0;1;39mThermal Daemon Service[0m...
Starting [0;1;39mLogin Service[0m...
Starting [0;1;39mAccounts Service[0m...
[[0;32m OK [0m] Started [0;1;39mSet the CPU Frequency Scaling governor[0m.
Starting [0;1;39mGRUB failed boot detection[0m...
Starting [0;1;39mDetect the available GPUs and deal with any system changes[0m...
[[0;32m OK [0m] Started [0;1;39mSave initial kernel messages after boot[0m.
Starting [0;1;39mSystem Logging Service[0m...
[[0;32m OK [0m] Reached target [0;1;39mSound Card[0m.
Starting [0;1;39mLSB: automatic crash report generation[0m...
Starting [0;1;39mDispatcher daemon for systemd-networkd[0m...
Starting [0;1;39mRemove Stale Online ext4 Metadata Check Snapshots[0m...
[[0;32m OK [0m] Started [0;1;39mRegular background program processing daemon[0m.
Starting [0;1;39mDisk Manager[0m...
[[0;32m OK [0m] Started [0;1;39mRun anacron jobs[0m.
[[0;32m OK [0m] Started [0;1;39mirqbalance daemon[0m.
Starting [0;1;39mRotate log files[0m...
Starting [0;1;39mModem Manager[0m...
Starting [0;1;39mAvahi mDNS/DNS-SD Stack[0m...
Starting [0;1;39mLSB: Record successful boot for GRUB[0m...
[[0;32m OK [0m] Started [0;1;39mACPI event daemon[0m.
[[0;32m OK [0m] Started [0;1;39mCUPS Scheduler[0m.
Starting [0;1;39mDiscard unused blocks on filesystems from /etc/fstab[0m...
[[0;32m OK [0m] Reached target [0;1;39mLogin Prompts[0m.
[[0;32m OK [0m] Started [0;1;39mD-Bus System Message Bus[0m.
Starting [0;1;39mWPA supplicant[0m...
Starting [0;1;39mNetwork Manager[0m...
Starting [0;1;39moFono Mobile telephony stack[0m...
Starting [0;1;39mDaily man-db regeneration[0m...
Starting [0;1;39mRestore /etc/resolv.conf if the system crashed before the ppp link was shut down[0m...
Starting [0;1;39mSnap Daemon[0m...
[[0;32m OK [0m] Started [0;1;39mLogin Service[0m.
[[0;32m OK [0m] Started [0;1;39mNetwork Name Resolution[0m.
[[0;32m OK [0m] Started [0;1;39mDetect the available GPUs and deal with any system changes[0m.
[[0;32m OK [0m] Started [0;1;39mRemove Stale Online ext4 Metadata Check Snapshots[0m.
[[0;32m OK [0m] Started [0;1;39mDiscard unused blocks on filesystems from /etc/fstab[0m.
[[0;32m OK [0m] Started [0;1;39mRestore /etc/resolv.conf if the system crashed before the ppp link was shut down[0m.
[[0;32m OK [0m] Started [0;1;39mGRUB failed boot detection[0m.
[[0;32m OK [0m] Started [0;1;39mLSB: automatic crash report generation[0m.
[[0;32m OK [0m] Started [0;1;39mLSB: Record successful boot for GRUB[0m.
[[0;32m OK [0m] Started [0;1;39mSystem Logging Service[0m.
[[0;32m OK [0m] Started [0;1;39moFono Mobile telephony stack[0m.
[[0;32m OK [0m] Started [0;1;39mWPA supplicant[0m.
[[0;32m OK [0m] Started [0;1;39mThermal Daemon Service[0m.
[[0;32m OK [0m] Started [0;1;39mAvahi mDNS/DNS-SD Stack[0m.
Starting [0;1;39mAuthorization Manager[0m...
Starting [0;1;39mManage, Install and Generate Color Profiles[0m...
Stopping [0;1;39mCUPS Scheduler[0m...
[[0;32m OK [0m] Reached target [0;1;39mHost and Network Name Lookups[0m.
[[0;32m OK [0m] Stopped [0;1;39mCUPS Scheduler[0m.
[[0;32m OK [0m] Started [0;1;39mCUPS Scheduler[0m.
[[0;32m OK [0m] Started [0;1;39mMake remote CUPS printers available locally[0m.
[[0;32m OK [0m] Started [0;1;39mNetwork Manager[0m.
Starting [0;1;39mNetwork Manager Wait Online[0m...
[[0;32m OK [0m] Reached target [0;1;39mNetwork[0m.
[[0;32m OK [0m] Started [0;1;39mUnattended Upgrades Shutdown[0m.
Starting [0;1;39mPermit User Sessions[0m...
[[0;32m OK [0m] Started [0;1;39mPermit User Sessions[0m.
Starting [0;1;39mSet console scheme[0m...
Starting [0;1;39mTerminate Plymouth Boot Screen[0m...```
