Troubleshooting · HOMELAB // k3s

#	Symptom	Cause	Fix
1	Windows installer requires network and a Microsoft account	default Win11 Home behaviour	Shift+F10 → `start ms-cxh:localonly`, Ventoy `VTOY_WIN11_BYPASS_NRO`
2	After installing Windows, USB no longer boots	Windows Boot Manager first in UEFI	Novo → Boot Menu → EFI USB Device
3	Ubuntu: Probing for devices to install to failed, `Invalid dep_id (disk-dm-1)`	Ventoy maps the ISO via device-mapper	Ventoy → Boot in grub2 mode
4	Ubuntu: no Add GPT Partition and no free space	in grub2 mode the installer did not scan gaps between partitions	`sgdisk -n 0:0:0 …` in the installer shell, then reboot
5	Wi-Fi does not work (not even a hotspot)	rfkill `soft=1` + empty `wifis: {}` in netplan	unblock via `/sys/class/rfkill/*/soft` + `50-wifi.yaml`
6	No `rfkill` in the installer	minimal environment	install without network, fix in the installed system
7	GRUB menu not shown	Ubuntu Server has `GRUB_TIMEOUT=0`	`GRUB_TIMEOUT_STYLE=menu`, `GRUB_TIMEOUT=5`
8	Windows listed twice in GRUB	`os-prober` + a manual entry in `40_custom`	remove the manual entry
9	Reservation on the ISP router has no effect	addresses are handed out by the own Wi-Fi router behind it	DHCP reservation on the router that is the gateway (`route -n get default`)
10	Flux: `apps` reports dependency ‘flux-system/infra’ is not ready	after a new commit `infra` syncs first (`dependsOn`)	nothing, it resolves shortly; to speed up: `flux reconcile kustomization apps`

Useful diagnostic commands

shell @ server

lsblk -o NAME,SIZE,MODEL,MOUNTPOINTS          # disks and partitions
sudo parted /dev/sda unit GiB print free      # including free space
grep . /sys/class/rfkill/*/{name,soft,hard}   # radio blocks
ip -br addr ; ip route                        # addresses and gateway
networkctl status wlp3s0 --no-pager           # Wi-Fi state
sudo journalctl -u ssh -n 20 --no-pager       # why SSH rejected a login
sudo sshd -T | grep -i auth                   # effective sshd config
sudo ufw status verbose                       # firewall
k get pods -A ; k get events -A --sort-by=.lastTimestamp | tail

Lessons learned

No network? Scripts on a USB disk: diagnostics and configuration as a script, with output saved to a file instead of retyping.
Test key login before disabling passwords, and keep a second SSH session open as a safety net.
Fixed IP before k3s: k3s writes the address into its certificates and kubeconfig.