Bug Report: ER605 v2 - SNMP Incoherency and Data Merging during WAN Failover
There is a critical discrepancy in how the SNMP agent reports interface statistics (IF-MIB) when the router enters Link Backup (Failover) mode. Currently, the router fails to maintain independent traffic accounting for physical ports during an emergency switch-over.
Observed Anomalous Behavior:
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Traffic Misassignment: When the Primary WAN (Port 1) goes offline, the router correctly routes traffic through the Backup WAN1 (Port 2). However, the SNMP agent begins reporting the Backup WAN1's traffic under the Primary WAN's index (1026) instead of its own physical index (1038).
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Loss of Granularity: Data counters for the Backup Port (1038) remain static or show negligible values, while the Primary Port index (which is physically disconnected/offline) acts as a "logical aggregator" for all global outbound traffic.
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Severe Update Latency: During failover, the SNMP
ifInOctetsandifOutOctetscounters update with extreme delay (often exceeding 120 seconds) and fail to reflect the actual throughput (e.g., a 180MB download is reported as <1MB).
Required Fix / Feature Request: It is essential that a future firmware update ensures strict physical port isolation for SNMP counters. Specifically:
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Independence: Traffic data must be exposed separately for each physical port at all times. The SNMP agent must not "merge" or "redirect" traffic statistics of the Backup WAN into the Primary WAN’s OID/Index during failover.
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Real-time Accuracy:
IF-MIBcounters must reflect the real-time bitstream of the physical silicon port, regardless of the logical routing state (Failover/Load Balance). -
Consistency: If 100MB passes through the physical pins of Port 2, those 100MB must appear under Index 1038, even if Port 1 is designated as the "Default Gateway."
Impact: The current behavior makes professional network monitoring (via Zabbix, PRTG, or custom scripts) impossible. Network administrators cannot accurately track data usage on backup lines (which often have data caps) because the router "hides" this traffic within the offline primary interface's counters.
As shown in the screenshot, Port 1(WAN) is Offline and Port 2 (WAN1) is Online, yet SNMP continues to report traffic on Port 1's index while Port 2 remains at zero. This proves the MIB database mapping is broken during Failover.
But it came out the same day, I must have missed it. Okay, I updated the firewall to version 2.3.3 build 20251029 rel.18054.
Unfortunately, the only changelog for this version compared to my previous one is: "1. Use a more secure signature algorithm to enhance device security." and nothing else.
I'll wait and see what happens. If so, I'll report it again and ask you to let the developers know what's needed for a fix.
thanks for now.
@Vincent-TP Here we are, just a short time later. Once again, the ER605 V2 switched traffic to WAN/LAN1 for no apparent reason and hasn't switched back. Furthermore, SNMP reading hasn't changed compared to the previous firmware. See how the backup WAN/LAN1 follows the WAN? Something's wrong, folks. Please report this specific issue.
in the attachment the full log of wans status (UP/DOWN) where you can see that the primary WAN is never gone down.
Serious: The router sets WAN/LAN1 as primary for no reason, even if I reboot the 4G router connected to WAN/LAN1, the ER605 router temporarily sets the primary WAN in use, BUT as soon as the 4G router comes back online it resets it as primary, this thing does not make sense.
