Array didn't auto-start because disk4 was initially missing
Nov 28 23:37:25 quasar-ultima kernel: mdcmd (5): import 4
Nov 28 23:37:25 quasar-ultima kernel: md: import_slot: 4 missing
It came back online a few seconds later, that's why you could then start the array manually:
Nov 28 23:37:45 quasar-ultima kernel: mdcmd (5): import 4 sdm 64 3907018532 0 WDC_WD40EFAX-68JH4N1_WD-WX42D410YUKV
Nov 28 23:37:45 quasar-ultima kernel: md: import disk4: (sdm) WDC_WD40EFAX-68JH4N1_WD-WX42D410YUKV size: 3907018532
So it's not an Unraid problem, check/replace cables on that disk.
There's something writing to the array, you can see that because there are writes to parity, and since there are no writes to any other disk, it's writing to disk2.
On the main GUI page click on the flash drive, scroll down to "Syslinux Configuration", make sure it's set to "menu view" (top right) and add that to your default boot option, after "append initrd=/bzroot"
This is npormal, not getting an IP from the DHCP server means there's a networking problem somewhere with the router, so it's expected using a static IP also won't work.