# PPPoE: PADI timeout, no Access Concentrator responded on interface eth0

- **ID:** `networking/pppoe-padi-timeout`
- **Domain:** networking
- **Category:** network_error
- **Verification:** ai_generated
- **Fix Rate:** 80%

## Root Cause

The PPPoE client sent a PPPoE Active Discovery Initiation (PADI) broadcast but received no PADO response from any Access Concentrator, indicating no PPPoE server on the network or a layer-2 issue.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| rp-pppoe 3.15 | active | — | — |
| Linux kernel 5.10 | active | — | — |
| OpenWrt 22.03 | active | — | — |

## Workarounds

1. **Check if the interface is connected to the correct VLAN: ip link show eth0 ; verify VLAN tagging matches the ISP requirement, e.g., vconfig add eth0 10 ; pppoe -I eth0.10** (85% success)
   ```
   Check if the interface is connected to the correct VLAN: ip link show eth0 ; verify VLAN tagging matches the ISP requirement, e.g., vconfig add eth0 10 ; pppoe -I eth0.10
   ```
2. **Run tcpdump to confirm no PADO is received: tcpdump -i eth0 -e -n 'ether proto 0x8863' ; if no packets, contact ISP or check physical connection** (80% success)
   ```
   Run tcpdump to confirm no PADO is received: tcpdump -i eth0 -e -n 'ether proto 0x8863' ; if no packets, contact ISP or check physical connection
   ```

## Dead Ends

- **** — If no AC exists, retrying the same broadcast will still time out; the network must have a PPPoE server. (90% fail)
- **** — PADI is a broadcast and typically not blocked; the issue is usually at the server side or VLAN mismatch. (65% fail)