Internet connectivity has become a critical requirement for businesses, offices, educational institutions, and service providers. To ensure uninterrupted connectivity, organizations often deploy multi-WAN routers such as the TP-Link Omada ER605 Gigabit Multi-WAN VPN Router. The ER605 supports load balancing and automatic failover between multiple Internet Service Providers (ISPs), providing redundancy and high availability.
A common issue reported by network administrators is that the ER605 does not automatically switch from the primary ISP connection (Airtel) to the backup ISP connection (Jio) when the Airtel internet service fails. However, when the Airtel router is completely powered off, the ER605 successfully shifts traffic to the Jio connection.
This article explains the causes of this issue, how WAN failover works, and the recommended configuration for reliable internet redundancy.
Example Deployment:
| Scenario | Result |
|---|---|
| Airtel internet fails but router remains powered ON | No automatic failover |
| Airtel router powered OFF | Failover to Jio works |
| Jio remains active and healthy | Working normally |
This behavior indicates that the router detects physical link failures but may not properly detect internet connectivity failures.
The ER605 determines WAN health using multiple methods:
The router checks:
If the Airtel modem remains powered on, the WAN port remains active.
The router checks:
Only when internet monitoring is correctly configured can the router distinguish between:
When Airtel service fails but the modem remains powered on:
Default Online Detection settings may not adequately verify real internet connectivity.
Firmware version:
2.0.1 Build 20220223
is an early release and lacks several failover improvements added in later versions.
Monitoring ISP gateway addresses instead of public internet servers may produce false-positive results.
Existing NAT sessions may remain tied to WAN1 even after WAN status changes.
Navigate to:
Transmission → Load Balancing → Online Detection
Configure WAN1:
| Parameter | Value |
| Mode | Manual |
| Ping | 8.8.8.8 |
| DNS Lookup | 1.1.1.1 |
Configure WAN2/WAN3:
| Parameter | Value |
| Mode | Manual |
| Ping | 8.8.4.4 |
| DNS Lookup | 1.0.0.1 |
These public DNS servers provide reliable internet reachability testing.
Navigate to:
Transmission → Load Balancing → Link Backup
Settings:
This ensures internet traffic automatically shifts to Jio when Airtel fails.
Traffic is distributed between multiple ISPs simultaneously.
Advantages:
Disadvantages:
One ISP remains active while another remains standby.
Advantages:
Recommended for most business offices.
Use public DNS servers:
Primary DNS:
8.8.8.8
Secondary DNS:
1.1.1.1
Avoid ISP-provided DNS servers whenever possible.
Incorrect Test:
Powering OFF the Airtel router.
This only tests physical link detection.
Correct Test:
Expected Result:
ping 8.8.8.8 -t
Observe packet loss during failover.
tracert 8.8.8.8
Confirm traffic is routed through Jio after failover.
nslookup myip.opendns.com resolver1.opendns.com
Verify that public IP changes from Airtel to Jio.
The installed firmware version is significantly outdated.
Benefits of upgrading:
Always:
When a TP-Link ER605 automatically switches to Jio only after the Airtel router is powered off, the issue is typically related to WAN health detection rather than failover functionality itself. The router continues to see the Airtel connection as active because the modem remains online, even though internet access may be unavailable.
Proper Online Detection settings, Link Backup configuration, public DNS monitoring, and firmware updates significantly improve automatic failover reliability. Implementing these recommendations ensures uninterrupted internet connectivity and minimizes business downtime during ISP outages.
