Router & Wi-Fi Error Codes: ISP Modems, DNS Failures, Authentication, and Drops

Use this guide to diagnose whether your outage is ISP-side, router/modem session state, DNS, Wi‑Fi quality, or VPN policy blocks.

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TL;DR

✓ Isolate: internet down for all devices or only Wi‑Fi?
✓ PPP/PPPoE errors often point to ISP provisioning, credentials, or negotiation.
✓ DNS failures can mimic “no internet”.
✓ VPN errors are often policy/firewall blocks; confirm requirements.

Quick Navigation

Symptoms Root Causes Step-by-step fixes What NOT to do If it persists Code directory Related guides & hubs FAQ References

Symptoms / When you see this

✓ Connected to Wi‑Fi but no internet.
✓ Intermittent drops.
✓ PPP/VPN errors like 734/735/809.
✓ DNS lookups fail.

Root causes (grouped)

✓ ISP outage/provisioning.
✓ Session negotiation failures (PPP/PPPoE).
✓ DNS/captive portal restrictions.
✓ Wi‑Fi interference and weak signal.
✓ VPN policy/firewall blocks.

Step-by-step fixes (safe, prioritized)

✓ Test wired connection to separate Wi‑Fi from ISP.
✓ Restart modem/router.
✓ Test DNS; try alternate DNS as a diagnostic.
✓ Verify PPPoE credentials/service type with ISP.
✓ Test VPN from another network and confirm required ports/protocols.

What NOT to do

✓ Do not factory reset first; capture settings.
✓ Do not open ports blindly; confirm security impact.
✓ Do not assume “no internet” is always ISP; DNS can be the culprit.

If it persists (escalation checklist)

✓ Capture errors, timestamps, and whether all devices are impacted.
✓ Collect modem status/signals if available.
✓ Contact ISP with exact PPP/connection errors and logs.

Code directory within this guide

✓ Router errors can be OS-originated messages (VPN/PPP). Use code page context to confirm where it was observed.

Code	Meaning	Next step
Error 734	PPP link control protocol terminated — A PPP/PPPoE session negotiation failed and the link control protocol was terminated.	Follow the checklist on the code page
Error 735	Requested address rejected — The remote server rejected the requested network address during connection setup.	Follow the checklist on the code page
Error 738	Server did not assign an address — The remote server did not assign an IP address during the connection process.	Follow the checklist on the code page
Error 789	L2TP connection failed — An L2TP/IPsec VPN connection could not be established due to negotiation or authentication failure.	Follow the checklist on the code page
Error 797	Modem not found — The connection could not be made because the modem or network device was not found or not ready.	Verify the correct path/resource and prerequisites
Error 806	VPN connection failed — A VPN connection could not be established, often due to blocked ports or protocol restrictions.	Follow the checklist on the code page
Error 807	Network connection interrupted — The VPN or remote connection was interrupted before it could complete.	Follow the checklist on the code page
Error 809	VPN tunnel could not be established — A VPN tunnel could not be established, commonly due to blocked ports or NAT/firewall configuration.	Follow the checklist on the code page
Error 812	Connection blocked by policy — A VPN/remote connection was blocked because the access policy did not allow the requested connection parameters.	Follow the checklist on the code page
Error 813	Existing broadband connection detected — A broadband connection attempt was blocked because a connection is already established or configured as always-on.	Follow the checklist on the code page
Error 619	Port disconnected — A connection attempt ended because the port was disconnected or the session was terminated.	Follow the checklist on the code page
Error 629	Connection closed — The remote endpoint closed the connection during session establishment.	Follow the checklist on the code page
Error 651	Connection failed — A PPP connection attempt failed and the session could not be established.	Follow the checklist on the code page
Error 678	No response — The remote endpoint did not respond during a connection attempt.	Follow the checklist on the code page
Error 691	Access denied — Authentication failed for a PPP connection, often due to credentials or permission.	Verify account permissions and security policy
Error 720	PPP control failed — A PPP control protocol could not be negotiated during connection setup.	Follow the checklist on the code page
Error 769	Destination not reachable — The specified destination was not reachable during a connection attempt.	Follow the checklist on the code page
Error 772	Dial-up failed — A connection attempt could not complete due to a device or link failure.	Follow the checklist on the code page
Error 815	Broadband connection failed — A broadband connection attempt failed to establish a working session.	Follow the checklist on the code page
Error 868	Remote connection not made — A connection attempt could not reach the remote access server.	Follow the checklist on the code page

Tip: If your exact code isn’t listed, use the closest hub link above and browse related prefixes or message patterns.

FAQ

How can DNS break internet if Wi‑Fi is connected?

The link can be up while name resolution fails. Without DNS, many apps cannot find servers.

Are PPPoE errors always wrong password?

Not always. Provisioning, line issues, and ISP policy can cause negotiation failures.

Fastest isolation test?

Try wired connection or hotspot to separate Wi‑Fi/router from ISP path.

Should I change Wi‑Fi security mode?

Usually not for drops. Address signal/interference first.

Why does VPN fail only on one network?

Firewalls/ISPs can block protocols. Testing on another network confirms policy blocks.

What should I tell ISP?

Exact error codes, timestamps, modem status, and whether other devices are impacted.

Is rebooting enough?

It often fixes transient state; repeated errors need configuration or ISP-side fixes.

Can strong signal still be unstable?

Yes. Interference and congestion can cause packet loss despite good signal strength.

References / Notes

✓ ISP support guidance
✓ Router logs and status pages
✓ VPN documentation from your provider