Error map
DHCPDISCOVER: no free leases Networking: dhcpd: DHCPDISCOVER from aa:bb:cc:dd:ee:ff via eth0: network 192.168.1.0/24: no free leases
Networking · layer 2, Network
Centre: this error. First ring: errors it is linked with (7). Outer ring: what those are linked with. Colours show the layer of a request each error belongs to. Click any dot to re-centre the map on it; hover to follow its connections. The centre dot opens the error page.
Directly related (7)
Networking: Windows has detected an IP address conflict / Duplicate address detected by 00:aa:bb:cc:dd:ee
Two devices on the same network are using the same IP address, so traffic reaches the wrong one or neither.
Networking: Port forwarding configured but the port stays closed — carrier-grade NAT (CGNAT) or double NAT
Your router forwards the port correctly, but another NAT in front of it (your ISP or a second router) blocks inbound connections.
Networking: IPv4 address 169.254.x.x (Autoconfiguration / APIPA) — the PC couldn't get an address from DHCP
With no DHCP answer, the computer gave itself a link-local 169.254.x.x address, which only works on the local segment.
Networking: Clients receive the wrong default gateway or DNS server — a rogue DHCP server (often a home router) answers first
A second DHCP server on the network is giving clients bad settings, so some machines have no internet or odd DNS.
Networking: `arp -n` shows (incomplete) / Destination Host Unreachable — no ARP reply from the next hop
The machine asked "who has this IP?" and nobody on the local network answered.
Networking: dhclient: DHCPDISCOVER on eth0 ... No DHCPOFFERS received. No working leases in persistent database - sleeping.
The client broadcast a DHCP request and no server answered.
Networking: connect: Cannot assign requested address — ephemeral port range exhausted by TIME_WAIT connections
The machine ran out of local ports for new outgoing connections to the same destination.
Two steps away (21)
Networking: Network cable unplugged / `ip link` shows NO-CARRIER state DOWN / Ethernet: Network cable unplugged
The network card sees no electrical link, so nothing above it (IP, DNS, browser) can work.
Networking: Windows: Default gateway is not available / Diagnose Connection Problems: DHCP not enabled
The PC can't reach its router, so it has no path out of the local network.
Networking: Two hosts on one LAN can't talk — subnet mask or network address mismatch
The hosts disagree about which addresses are local, so one tries to route traffic that should go straight across the LAN.
ssh: connect to host x port 22: Connection timed out
SSH packets get no reply — a firewall/security group drops them, the server is off, or the IP is wrong.
Networking: Wi-Fi keeps disconnecting / signal -80 dBm / wlan0: deauthenticating by local choice (reason=3)
The wireless link is too weak or too noisy to hold, so the client drops and rejoins repeatedly.
Networking: Interface down — SFP transceiver Loss of Signal / no receive light
A fibre or SFP link is down because the transceiver receives no light.
Docker Desktop: WSL 2 installation is incomplete / WSL update required
Docker Desktop on Windows needs WSL 2 and its Linux kernel; they’re missing, outdated or disabled.
Networking: PING: transmit failed. General failure. / ping: sendmsg: Operation not permitted
The operating system could not even send the packet, so the problem is local (adapter, route or firewall), not the remote host.
Networking: Your Remote Desktop Services session has ended. Possibly the network connection was lost / Remote Desktop disconnected, error code 0x904
An established Remote Desktop session dropped because the network under it stalled or the session was reset.
HTTP 502 Bad Gateway
A proxy or gateway (Nginx, load balancer, CDN) got an invalid response — or no response — from the upstream server behind it.
HTTP 504 Gateway Timeout
A proxy or gateway waited too long for the upstream server to respond and gave up.
Error creating: pods is forbidden: violates PodSecurity "restricted:latest": allowPrivilegeEscalation != false ...
The namespace enforces a Pod Security Standard (baseline/restricted) and the pod spec breaks one of its rules.
Networking: No Wi-Fi networks found — the Wi-Fi adapter is missing, disabled or its driver failed
The operating system doesn't see a working wireless adapter, so no networks can be listed.
Networking: wlan0: WPA: 4-way handshake failed - pre-shared key may be incorrect / WRONG_KEY
The Wi-Fi association started but key negotiation failed, almost always a wrong password.
Networking: Duplex mismatch — late collisions, runts and CRC errors on the switch port
One side runs full duplex and the other half duplex, so the link works but is slow and drops packets.
Networking: %CDP-4-NATIVE_VLAN_MISMATCH / device on the wrong VLAN can't reach the gateway
A port or trunk carries a different VLAN than expected, so hosts silently land on the wrong network.
Networking: kernel: nf_conntrack: table full, dropping packet — new connections fail on a Linux firewall/NAT host
The connection-tracking table is full, so the kernel drops packets for any new connection.
Networking: kernel: nfs: server nas01 not responding, still trying / nfs: server nas01 OK
An NFS client can't get replies from the server, so processes using the mount hang in uninterruptible sleep.
Networking: %SW_MATM-4-MACFLAP_NOTIF: Host is flapping between ports / broadcast storm
A layer-2 loop is making frames circle the network, saturating links and making the whole VLAN crawl.
Networking: %PM-4-ERR_DISABLE: psecure-violation error detected on Gi0/5, putting Gi0/5 in err-disable state
The switch shut the port down because a security or protection feature detected a violation.
Networking: SSH/HTTPS connects but hangs on large data — path MTU discovery black hole
Small packets pass but full-size ones vanish, so logins work and then transfers or page loads stall.
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