Asus RT-BE88U SFP instability problem

[ayacheomarrtv]

I have a problem with the instability of the SFP unit, as it does not stabilize at a speed of 2500 Mbps. There is an explanatory video for the problem.

Jan 1 01:12:46 kernel: SFP Module at Address 7 Core 0 is Unplugged
Jan 1 01:12:47 kernel: eth9 (Int switch port: 6) (Logical Port: 6) (phyId: 7) Link DOWN.
Jan 1 01:12:52 kernel: Opticaldet Unknown Transceiver
Jan 1 01:12:52 kernel: Module Form Factor: SFP/SFP+
Jan 1 01:12:52 kernel: Module Type : UNKNOWN
Jan 1 01:12:52 kernel: Vendor Name : ODI
Jan 1 01:12:52 kernel: Part Number : DFP-34X-2CY2
Jan 1 01:12:52 kernel: Part REV : 000
Jan 1 01:12:52 kernel: ************************************************************************
Jan 1 01:12:52 kernel: * Opticaldet: Unknown optical module - using default configuration *
Jan 1 01:12:52 kernel: * Please make sure the optical module is correct for your connection *
Jan 1 01:12:52 kernel: ************************************************************************
Jan 1 01:12:53 kernel: SFP Module is Plugged in at Serdes address 7 core 0 lane 0
Jan 1 01:13:03 pppd[4406]: Timeout waiting for PADO packets
Jan 1 01:14:18 pppd[4406]: Timeout waiting for PADO packets
Jan 1 01:14:20 kernel: Serdes 7 False Link Up with Error Symbols 0x0000 at 3.c466h at speed 1000Mbps mode USXGMII
Jan 1 01:14:25 kernel: eth9 (Int switch port: 6) (Logical Port: 6) (phyId: 7) Link Up at 1000 mbps full duplex AN: Off
Jan 1 01:14:39 kernel: eth9 (Int switch port: 6) (Logical Port: 6) (phyId: 7) Link DOWN.
Jan 1 01:14:44 kernel: Serdes 7 False Link Up with Error Symbols 0x0000 at 3.c466h at speed 2500Mbps mode USXGMII
Jan 1 01:14:47 kernel: eth9 (Int switch port: 6) (Logical Port: 6) (phyId: 7) Link Up at 2500 mbps full duplex AN: Off
Jan 1 01:15:01 kernel: eth9 (Int switch port: 6) (Logical Port: 6) (phyId: 7) Link DOWN.
Jan 1 01:15:07 kernel: Serdes 7 False Link Up with Error Symbols 0x0000 at 3.c466h at speed 1000Mbps mode USXGMII
Jan 1 01:15:12 kernel: eth9 (Int switch port: 6) (Logical Port: 6) (phyId: 7) Link Up at 1000 mbps full duplex AN: Off
Jan 1 01:15:33 pppd[4406]: Timeout waiting for PADO packets

 

[Ripshod]

Is this module on the compatible devices list? Seems it's not.

 

[ayacheomarrtv]

Is this module on the compatible devices list? Seems it's not.

odi dfp 34x 2cy2

 

[MrRojano97]

Since the RT-BE88U doesn’t recognize the ODI module as a known SFP, it applies a generic profile to it. As a result, the router only establishes a 1 Gbps link, even though the module is capable of 2.5 Gbps.

From what I’ve gathered in various forums, the only reliable fix appears to be modifying the Vendor ID and Part Number of the ODI (EEPROM) module to match those of the Huawei MA5671A. This allows the router to apply the Linux kernel’s SFP quirk patches, which unlock the full capabilities of the module, including 2.5 Gbps connectivity. (You need external Tools)

There’s another workaround—setting the LAN SDS mode to 4—but (according to other users), this can lead to frequent connection instability or complete loss of link, especially since the vendor ID isn’t recognized by the Asus firmware. So I’d consider this option risky.

The last option is to wait for Asus (or Asuswrt-Merlin) to officially recognize the ODI module and treat it like the MA5671A by applying the same kernel quirk patches. If this happens, the module should work out of the box at 2.5 Gbps without any manual modifications.

For reference, I’m using the DFP-34X-2C3 model (which is essentially the same as the 2C2, just with an APC connector), and I’ve observed the same behavior.

One more thing I noticed: when the generic profile is used, my Wi-Fi upload speeds drop significantly—on 160 MHz channels, I can only reach around 450 Mbps, whereas I’d normally expect 800–940 Mbps. This seems to be another side effect of the module not being properly initialized.

 

[void666]

Since the RT-BE88U doesn’t recognize the ODI module as a known SFP, it applies a generic profile to it. As a result, the router only establishes a 1 Gbps link, even though the module is capable of 2.5 Gbps.

From what I’ve gathered in various forums, the only reliable fix appears to be modifying the Vendor ID and Part Number of the ODI (EEPROM) module to match those of the Huawei MA5671A. This allows the router to apply the Linux kernel’s SFP quirk patches, which unlock the full capabilities of the module, including 2.5 Gbps connectivity. (You need external Tools)

There’s another workaround—setting the LAN SDS mode to 4—but (according to other users), this can lead to frequent connection instability or complete loss of link, especially since the vendor ID isn’t recognized by the Asus firmware. So I’d consider this option risky.

The last option is to wait for Asus (or Asuswrt-Merlin) to officially recognize the ODI module and treat it like the MA5671A by applying the same kernel quirk patches. If this happens, the module should work out of the box at 2.5 Gbps without any manual modifications.

For reference, I’m using the DFP-34X-2C3 model (which is essentially the same as the 2C2, just with an APC connector), and I’ve observed the same behavior.

One more thing I noticed: when the generic profile is used, my Wi-Fi upload speeds drop significantly—on 160 MHz channels, I can only reach around 450 Mbps, whereas I’d normally expect 800–940 Mbps. This seems to be another side effect of the module not being properly initialized.

Hey, thanks for information. I have a few questions, How to set LAN SDS mode? Can I tweak some settings in asus nvram to make it work?