I’m using a Vigor 2866ax that originally came with BT‑branded firmware (4.5.2_BT). I’ve now upgraded successfully to the standard DrayTek firmware (4.5.2_STD) using the Firmware Upgrade Utility. The upgrade completed without issues, but the LAN port problems that existed before the firmware change are still present.

Symptoms

1. LAN Port 5 is completely non‑functional
   • No link light at all
   • No connection with any known‑good Cat6 cable
   • No connection with any device (laptop, switch, AP)
   • Behaviour unchanged before and after firmware upgrade
2. Only three LAN ports negotiate at 1Gbps
   • The fourth active port always negotiates at 100Mbps
   • Tested with multiple known‑good devices and cables
   • The same device/cable negotiates at 1Gbps on other ports
   • LED colour confirms 100Mbps link
   • Behaviour unchanged before and after firmware upgrade
3. No per‑port switch controls or diagnostics available
   • The 2866ax does not expose “LAN → Switch Control” or “Port Status”
   • No way to force link speed or view per‑port negotiation
   • VLAN settings appear normal and unchanged
   • Syslog shows link up/down events but no detailed PHY information

What I’ve already tried

• Upgraded from BT firmware to official DrayTek firmware (4.5.2_STD)
• Rebooted and factory‑reset the router
• Tested with multiple Cat6 cables
• Tested with multiple devices that all negotiate 1Gbps elsewhere
• Verified that no VLAN or rate‑limit settings are affecting ports
• Confirmed that the UI is functioning normally and no menus are missing on STD firmware

What I’m trying to determine

Given that:

• One port is completely dead
• Another port is stuck at 100Mbps
• The behaviour is identical across BT and STD firmware
• Cables and devices have been ruled out
• No switch‑chip configuration options exist on this model

I’m trying to confirm whether this points to a hardware fault in the internal switch chip or if there are any hidden diagnostics, logs, or steps I can take to verify the condition of the LAN ports before replacing the unit.Any guidance from DrayTek support or other users who have seen similar symptoms would be appreciated.

Hi seb,

I’m using a Vigor 2866ax that originally came with BT‑branded firmware (4.5.2_BT). I’ve now upgraded successfully to the standard DrayTek firmware (4.5.2_STD) using the Firmware Upgrade Utility.

This isn't really branding, this is just for compatability. The _BT firmware is produced to make sure the units, with ADSL features, work correctly with the BT ADSL network. 
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• LAN Port 5 is completely non‑functional
  • No link light at all
  • No connection with any known‑good Cat6 cable
  • No connection with any device (laptop, switch, AP)
  • Behaviour unchanged before and after firmware upgrade

No per‑port switch controls or diagnostics available

• The 2866ax does not expose “LAN → Switch Control” or “Port Status”
• No way to force link speed or view per‑port negotiation

Have you checked the 'Panel Control' options yet?:  "System Maintenance >> Panel Control >> LAN Ports"
This is where the local LAN ports are enabled/disabled and link speed is shown. (Even though you did perform a 'Factory Reset', it's worth checking)
There are also 'Port' commands for setting link speed via the command line. See page 119 of the:  DrayTek Vigor Router CLI Reference doc . 
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• Only three LAN ports negotiate at 1Gbps
  • The fourth active port always negotiates at 100Mbps
  • Tested with multiple known‑good devices and cables
  • The same device/cable negotiates at 1Gbps on other ports
  • LED colour confirms 100Mbps link
  • Behaviour unchanged before and after firmware upgrade

Check that all pins are correctly aligned and not broken within the port. If only one pin doesn't make contact properly, the link will drop from 1Gbps down to 100Mbps.


Other than these checks, then yes, I would say you have hardware issues and need to either renew the unit or attempt some avenue for repair; i.e. warranty or repair shop...