Hey folks,
I’m slowly losing my mind over this one and would really appreciate any input.
I’ve got a real-world deployment with a MikroTik RBLHGGR unit:
The Setup:
• Router: MikroTik LHGG LTE6
• RouterOS: 7.19.1
• Power: Passive PoE (tested with the original and multiple other 24V injectors)
• Cable: Fixed ~20 m CAT7, in-wall, certified and tested by an electrician
• Switch: TP-Link smart-managed 1 Gbit switch (also tested with others)
• Install: Router is on the roof, PoE and switch are in the basement
The Problem:
Every time I install the device:
• It boots, negotiates 1 Gbit/s on ether1
• After some time (minutes or hours), link flaps begin and it eventually falls back to 100 Mbit/s
• Once it’s at 100 Mbit – it stays there
• Log shows interface down/up flapping
• LTE interface is stable, no drops there
• Issue happens with two different devices
What I’ve tested:
• Swapped devices (same model): same problem
• Fresh config from scratch: still flaps
• No VLANs, no firewall, no queueing
• Multiple PoE injectors tested (24V passive)
• Cabling was verified – no damage, no attenuation issues
• Tried different switches – same result
I’m out of ideas.
I’ve tried everything short of ripping out the in-wall CAT7 cable (which I’d really prefer not to do).
Did anyone ever encounter this kind of “Ether1 starts at 1 Gbit and slowly dies back to 100 Mbit” scenario?
Any help is appreciated – I’m happy to share exports, config. I logged a ticket with Support a few seconds ago, too. Maybe you guys have some ideas too
As a “dirty-fix” I created a small script to just reset the interface - because afterwards it always synchronizes to Gbit.
Thanks in advance,
Florian
[admin@mt-01] > /log/print where topics~"interface|script"
2025-06-11 16:54:04 interface,info lo link up
2025-06-11 16:54:04 interface,info back-to-home-vpn link up
2025-06-11 16:54:13 interface,info ether1 link up (speed 1G, full duplex)
2025-06-11 16:54:40 interface,info lte1 link up
2025-06-11 18:49:20 interface,info ether1 link down
2025-06-11 18:49:23 interface,info ether1 link up (speed 1G, full duplex)
2025-06-11 20:09:30 interface,info ether1 link down
2025-06-11 20:09:32 interface,info ether1 link up (speed 1G, full duplex)
2025-06-11 20:10:32 interface,info ether1 link down
2025-06-11 20:10:36 interface,info ether1 link up (speed 1G, full duplex)
2025-06-11 20:10:37 interface,info ether1 link down
2025-06-11 20:10:43 interface,info ether1 link up (speed 1G, full duplex)
2025-06-11 20:10:54 interface,info ether1 link down
2025-06-11 20:11:01 interface,info ether1 link up (speed 1G, full duplex)
2025-06-11 20:11:22 interface,info ether1 link down
2025-06-11 20:11:25 interface,info ether1 link up (speed 1G, full duplex)
2025-06-11 20:11:36 interface,info ether1 link down
2025-06-11 20:11:39 interface,info ether1 link up (speed 1G, full duplex)
2025-06-11 20:11:40 interface,info ether1 link down
2025-06-11 20:11:50 interface,info ether1 link up (speed 1G, full duplex)
2025-06-11 20:23:02 interface,info ether1 link down
2025-06-11 20:23:05 interface,info ether1 link up (speed 1G, full duplex)
2025-06-11 20:56:51 interface,info ether1 link down
2025-06-11 20:56:54 interface,info ether1 link up (speed 1G, full duplex)
2025-06-11 20:56:55 interface,info ether1 link down
2025-06-11 20:56:58 interface,info ether1 link up (speed 1G, full duplex)
2025-06-11 20:56:59 interface,info ether1 link down
2025-06-11 20:57:01 interface,info ether1 link up (speed 1G, full duplex)
2025-06-11 20:57:02 interface,info ether1 link down
2025-06-11 20:57:04 interface,info ether1 link up (speed 1G, full duplex)
2025-06-11 20:57:50 interface,info ether1 link down
2025-06-11 20:57:53 interface,info ether1 link up (speed 1G, full duplex)
2025-06-11 21:36:03 interface,info ether1 link down
2025-06-11 21:36:05 interface,info ether1 link up (speed 1G, full duplex)
2025-06-11 21:36:08 interface,info ether1 link down
2025-06-11 21:36:10 interface,info ether1 link up (speed 1G, full duplex)
2025-06-11 21:36:11 interface,info ether1 link down
2025-06-11 21:36:14 interface,info ether1 link up (speed 1G, full duplex)
2025-06-11 21:36:15 interface,info ether1 link down
2025-06-11 21:36:20 interface,info ether1 link up (speed 1G, full duplex)
2025-06-11 21:36:21 interface,info ether1 link down
2025-06-11 21:36:23 interface,info ether1 link up (speed 1G, full duplex)
2025-06-11 21:36:24 interface,info ether1 link down
2025-06-11 21:36:26 interface,info ether1 link up (speed 100M, full duplex)
2025-06-12 05:30:49 script,warning Resetting interface ether1 due to degraded state...
2025-06-12 05:31:04 interface,info ether1 link down
2025-06-12 05:31:08 interface,info ether1 link up (speed 1G, full duplex)
2025-06-12 05:31:09 script,warning Interface ether1 reset completed.
2025-06-12 06:14:20 script,warning Resetting interface ether1 due to degraded state...
2025-06-12 06:14:35 interface,info ether1 link down
2025-06-12 06:14:38 interface,info ether1 link up (speed 1G, full duplex)
2025-06-12 06:14:40 script,warning Interface ether1 reset completed.
2025-06-12 06:16:22 interface,info ether1 link down
2025-06-12 06:16:25 interface,info ether1 link up (speed 1G, full duplex)
2025-06-12 06:20:31 interface,info ether1 link down
2025-06-12 06:20:34 interface,info ether1 link up (speed 1G, full duplex)
2025-06-12 06:20:36 interface,info ether1 link down
2025-06-12 06:20:39 interface,info ether1 link up (speed 1G, full duplex)
2025-06-12 06:20:55 interface,info ether1 link down
2025-06-12 06:20:58 interface,info ether1 link up (speed 1G, full duplex)
2025-06-12 06:21:10 script,warning Resetting interface ether1 due to degraded state...
2025-06-12 06:21:25 interface,info ether1 link down
2025-06-12 06:21:29 interface,info ether1 link up (speed 1G, full duplex)
2025-06-12 06:21:30 script,warning Interface ether1 reset completed.
2025-06-12 06:26:18 interface,info ether1 link down
2025-06-12 06:26:21 interface,info ether1 link up (speed 1G, full duplex)
2025-06-12 06:26:26 interface,info ether1 link down
2025-06-12 06:26:28 interface,info ether1 link up (speed 1G, full duplex)
2025-06-12 06:26:47 interface,info ether1 link down
2025-06-12 06:26:49 interface,info ether1 link up (speed 1G, full duplex)
2025-06-12 06:31:30 interface,info ether1 link down
2025-06-12 06:31:33 interface,info ether1 link up (speed 1G, full duplex)
2025-06-12 06:46:59 interface,info ether1 link down
2025-06-12 06:47:01 interface,info ether1 link up (speed 1G, full duplex)
2025-06-12 06:47:13 interface,info ether1 link down
2025-06-12 06:47:15 interface,info ether1 link up (speed 1G, full duplex)
2025-06-12 06:47:25 interface,info ether1 link down
2025-06-12 06:47:27 interface,info ether1 link up (speed 1G, full duplex)
2025-06-12 06:47:40 interface,info ether1 link down
2025-06-12 06:47:43 interface,info ether1 link up (speed 1G, full duplex)
2025-06-12 06:47:45 interface,info ether1 link down
2025-06-12 06:47:51 interface,info ether1 link up (speed 1G, full duplex)
2025-06-12 06:47:55 interface,info ether1 link down
2025-06-12 06:47:57 interface,info ether1 link up (speed 1G, full duplex)
2025-06-12 06:48:01 interface,info ether1 link down
2025-06-12 06:48:03 interface,info ether1 link up (speed 1G, full duplex)