Cannot see the beginning of the problem but the device dropped offline, this is usually a power/connection problem, also see here for better pool monitoring so you are alerted as soon as there is a problem.
That hangcheck message comes for the watchdog timer, it might suggest it's starting to detect a hung system, but it's it should not be the cause for it.
Syslog is full due to these repeating USB related issues:
Oct 5 02:57:19 Tower kernel: usb 3-2: USB disconnect, device number 70
Oct 5 02:57:19 Tower usb_manager: Info: rc.usb_manager usb_remove dresden_elektronik_ingenieurtechnik_GmbH_ConBee_II_DE2434358 /dev/bus/usb/003/070 003 070
Oct 5 02:57:19 Tower usb_manager: Info: rc.usb_manager Device Match 003/070 vm: Home Assistant 003 070
Oct 5 02:57:19 Tower usb_manager: Info: connect as serial guest port is:04
Oct 5 02:57:19 Tower usb_manager: Info: virsh called Home Assistant 003 070 Device detach request sent successfully
Oct 5 02:57:19 Tower usb_manager: Info: rc.usb_manager Disconnect 003/070 vm: Home Assistant running 003 070
Oct 5 02:57:19 Tower usb_manager: Info: rc.usb_manager Removed 003/070 vm: Home Assistant running 003 070
Oct 5 02:57:19 Tower kernel: usb 3-2: new full-speed USB device number 71 using xhci_hcd
Oct 5 02:57:19 Tower kernel: cdc_acm 3-2:1.0: ttyACM0: USB ACM device
Oct 5 02:57:19 Tower usb_manager: Info: rc.usb_manager usb_add dresden_elektronik_ingenieurtechnik_GmbH_ConBee_II_DE2434358 /dev/bus/usb/003/071 003 071
Oct 5 02:57:20 Tower usb_manager: Info: rc.usb_manager Add device with more than one interface & connect serial yes .
Oct 5 02:57:20 Tower usb_manager: Info: rc.usb_manager unable to connect device as Serial device details unknown for dresden_elektronik_ingenieurtechnik_GmbH_ConBee_II_DE2434358.
Oct 5 02:57:20 Tower usb_manager: Info: rc.usb_manager tty_add dresden_elektronik_ingenieurtechnik_GmbH_ConBee_II_DE2434358 /dev/ttyACM0
Oct 5 02:57:20 Tower usb_manager: Info: rc.usb_manager Processing tty attach dresden_elektronik_ingenieurtechnik_GmbH_ConBee_II_DE2434358 /dev/ttyACM0 003 071
Oct 5 02:57:20 Tower usb_manager: Info: rc.usb_manager Add device with more than one interface & connect serial yes 1 1.
Oct 5 02:57:20 Tower usb_manager: Info: rc.usb_manager Autoconnect vm state:running dresden_elektronik_ingenieurtechnik_GmbH_ConBee_II_DE2434358 running 003 071
Oct 5 02:57:20 Tower usb_manager: Info: connect as serial guest port is:04
Oct 5 02:57:20 Tower usb_manager: Info: virsh called Home Assistant 003 071 Device attached successfully
Oct 5 02:57:23 Tower kernel: usb 3-2: USB disconnect, device number 71
Oct 5 02:57:23 Tower usb_manager: Info: rc.usb_manager usb_remove dresden_elektronik_ingenieurtechnik_GmbH_ConBee_II_DE2434358 /dev/bus/usb/003/071 003 071
Oct 5 02:57:23 Tower usb_manager: Info: rc.usb_manager Device Match 003/071 vm: Home Assistant 003 071
Oct 5 02:57:23 Tower usb_manager: Info: connect as serial guest port is:04
Oct 5 02:57:23 Tower usb_manager: Info: virsh called Home Assistant 003 071 Device detach request sent successfully
It's logged as disk problem, you can run an extended SMART test to confirm, it it fails replace it, or depending on the situation, you might try to do a full disk write, pending sectors should go back to zero then see if they come back again soon or not.
Do you mean a new Unraid install, it asked to create a password and that part worked and then it won't login? If yes make sure you try a different browser, also that there are no ad-blockers or similar installed. You can also grab the diagnostics from the console in case they show something.
First note that bonding (if correctly configured and supported) will only speed up multiple transfers, single transfer will still only use one NIC.
Transfer starting at 110MB/s suggests the LAN is working correctly, then the devices are not able to keep up, do you get the same speed if transferring to array or cache? You should also post the diagnostics mostly to look at the hardware used.
It is PCIe 3.0, you should expect 400MB/s+ per device with 8 devices, assuming no DMI bottlenecks, but more than enough or 8 HDDs, with a x1 link there would be a bottleneck, if it works, I remember some LSI HBAs not working at x1.
Correct, and it's a PCH slot, i.e., it shares the DMI bandwidth with the onboard SATA controller, one m.2 slot, other PCIe slots, etc.
Yes, if the m.2 slot is set to x2.
I guess it depends on how you try to fix it, I've used and told other users to use gdisk before to fix and there never was any data loss, but if gdisk doesn't find a problem don't know how you plan to do it.
Note seeing anything relevant logged, that together with fdisk not detecting any issues would make me not worry, but if you to find out which disk is causing the warning you'd probably need to disconnect all devices and try booting with one at a time.