AdguardTeam/AdGuardHome · error

hostname: %w

Error message

hostname: %w

What it means

addLease found that another lease already owns the requested hostname in hostsIndex, so it returns the hostname wrapped around errors.ErrDuplicated. The DHCP server enforces unique hostnames across leases so DNS/RDNS entries stay unambiguous.

Source

Thrown at internal/dhcpd/v4_unix.go:335

func (s *v4Server) addLease(l *dhcpsvc.Lease) (err error) {
	r := s.conf.ipRange
	leaseIP := net.IP(l.IP.AsSlice())
	offset, inOffset := r.offset(leaseIP)

	if l.IsStatic {
		// TODO(a.garipov, d.seregin): Subnet can be nil when dhcp server is
		// disabled.
		if sn := s.conf.subnet; !sn.Contains(l.IP) {
			return fmt.Errorf("subnet %s does not contain the ip %q", sn, l.IP)
		}
	} else if !inOffset {
		return fmt.Errorf("lease %s (%s) out of range, not adding", l.IP, l.HWAddr)
	}

	// TODO(e.burkov):  l must have a valid hostname here, investigate.
	if l.Hostname != "" {
		if _, ok := s.hostsIndex[l.Hostname]; ok {
			return fmt.Errorf("hostname: %w", errors.ErrDuplicated)
		}

		s.hostsIndex[l.Hostname] = l
	}
	s.ipIndex[l.IP] = l

	s.leases = append(s.leases, l)
	s.leasedOffsets.set(offset, true)

	return nil
}

// rmLease removes a lease with the same properties.
func (s *v4Server) rmLease(lease *dhcpsvc.Lease) (err error) {
	if len(s.leases) == 0 {
		return nil
	}

View on GitHub (pinned to b41aefbe51)

Solutions

1. Rename one of the conflicting clients' hostnames
2. Remove or expire the stale lease holding the hostname (or reset leases)
3. When resetting leases in bulk, deduplicate hostnames before insertion

Example fix

// before
{ hostname: "printer", mac: "aa:.." }
{ hostname: "printer", mac: "bb:.." }

// after
{ hostname: "printer", mac: "aa:.." }
{ hostname: "printer-2", mac: "bb:.." }

// dedupe hostnames before bulk add/reset
seen := map[string]bool{}
for _, l := range leases {
    if l.Hostname != "" && seen[l.Hostname] { l.Hostname = "" }
    seen[l.Hostname] = true
}

if err := srv.addLease(l); errors.Is(err, errors.ErrDuplicated) {
    // rename or clear the hostname and retry
}

When it happens

Trigger: Adding or resetting a lease whose Hostname already exists in s.hostsIndex under a different MAC/IP — e.g. two devices both claiming hostname "android-abc123", or re-adding a lease set containing a duplicate hostname.

Common situations: Cloned VMs/IoT devices with identical default hostnames; importing a lease file with duplicates; replacing a device while its old lease still holds the hostname.

Related errors

• no valid parts
• login: %w
• another client %q uses the same ClientID %q
• another client %q uses the same IP %q
• another client %q uses the same subnet %q

AI-assisted analysis of AdguardTeam/AdGuardHome@b41aefbe51 (2026-08-27). Data as JSON: /api/errors/7617ca5220a71357. Report an issue: GitHub.