Looks like host is just too small with 4GB of memory.
Strange that you still have warning without running VMs.
But you can export system logs from vSpher client: File / Export diagnostic data.
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MCSA, MCTS Hyper-V, VCP 3/4, VMware vExpert
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EMCCAe, HPE ASE, MCITP: SA+VA, VCP 3/4/5, VMware vExpert XO (14 stars)
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