My network configuration uses two antennas in bridge mode to transmit internet signal across two houses, the source has the ISP modem and in my house there is the router (Xiaomi Mi Router 4A Gigabit Edition) with openwrt that receives it. I've had this problem where after a power outage, when the devices would come back online my speed was very limited - around 10mbps, whereas normally it is ~80mbps - and I always thought that it was a problem with the antennas, since to solve it I always just rebooted them.
Recently though I discovered that while the issue persist my antennas still communicate at the expected speeds and the problem is corrected also by just unplugging and plugging back in the ethernet cable that goes from the receiving antenna in my home to the router (and I'm guessing also rebooting the router would correct the issue), so it seems like the issue is happening at the router level.
I don't remember whether the issue popped up after installing openwrt since I've been using it for a while, but the weird thing is that the issue happens both when the power outage affects only my house and when it affects only the house of the source (and obviously also when there is a power outage in both places at the same time), so it is not just the power being cut from the router that causes the problem, and I am unable to identify the source
Hi groda,
By “antenna”, do you mean “Access Point”? Also, I don’t know how your network is layed out…
Have you tried checking the ethernet speed (10 | 1000 | 1000) mbps of the connection from your router to the “antenna”? Specifically checking it when you notice the slowdown problem, and then after unplugging&plugging-back-in… ?
ethtool <interface> or to parse out the more important fields ethtool <interface> | grep Speed
For me, I have lan2 plugged into an older device and I see:
root@MyHost:~# ethtool lan2 | grep Speed
Speed: 100Mb/s
If the slowdown is caused by a marginal ethernet cable run, for instance (and this has happened to me**), then comparisons before and after could help you confirm/refute that this might be the problem.
** I had to replace a cable once because it developed a kink in it when being fed through. Also I had a poor connection/seating of a plug end to an ethernet jack, cause by just a bit of tension on the cable.
here's how y network is layed out:
in the "source" house there is the ISP modem and a long range antenna plugged into it. The antenna is set to bridge mode and in the modem I set it to DMZ mode in the absence of a bridge mode. This antenna communicates with a receiving antenna in another house that ends up in the openwrt router with an ethernet cable
┌──────────┐
│ ISP modem │
└──────────┘
DMZ
│
│eth cable
│
antenna
(bridge mode)
..
..
..
..
.. wireless
..
..
..
..
..
antenna
(bridge mode)
│
│
│
│
┌──────────────┐
│ openwrt router │
└──────────────┘
I’d exclude the possibility of a faulty cable since the issue can be consistently corrected even without touching any cable.
Also I’ll try checking the speed between the router and the antenna when the problem comes back, but last time I tried doing a speed test plugging the ethernet cable from the receiving antenna directly into a pc (while the issue was occurring) and it came out fine, and then when plugging it back into the router it was gone (it never just fixes itself, so it obviously was fixed by the action of unplugging and plugging the cable back in)
What kind of antenna has an ethernet cable?
What is the OpenWRT router, please show output of
ubus call system board
This is the kind of antenna I’m talking about. I’m using it exactly for its purpose so it should make my layout clearer.
root@OpenWrt:~# ubus call system board
{
"kernel": "6.6.104",
"hostname": "OpenWrt",
"system": "MediaTek MT7621 ver:1 eco:3",
"model": "Xiaomi Mi Router 4A Gigabit Edition",
"board_name": "xiaomi,mi-router-4a-gigabit",
"rootfs_type": "squashfs",
"release": {
"distribution": "OpenWrt",
"version": "24.10.3",
"revision": "r28872-daca7c049b",
"target": "ramips/mt7621",
"description": "OpenWrt 24.10.3 r28872-daca7c049b",
"builddate": "1758316778"
}
}
It is something more then an Antenna it is a complete radio with ethernet port.
So follow the advice of @davygravy install ethtool and while you are at it better upgrade to 24.10.5.
Maybe your ethernet port of the router has gone back to 10 Mb/s.
With ethtool you can check and set speed etc.
It happened again,
root@OpenWrt:~# ethtool wan | grep Speed
Speed: 10Mb/s
restarting the WAN interface did nothing, but after a router reboot
root@OpenWrt:~# ethtool wan | grep Speed
Speed: 100Mb/s
The issue wasn’t solved though
sorry, it’s a language barrier thing
Next time it happens use ethtool to set the speed to 100 Mb/s
if that works then make a hotplug script to set that speed on ifup of your wan interface
unfortunately even if after a reboot it went back to 100mbps, the issue is persisting this time. Not even unplugging and plugging back the ethernet cable from the router had any effect, only rebooting both radio devices was able to fix it. I’m really lost on where the issue lies here
Have you used the ethtool to set the speed back to the desired speed?
when the issue comes back I’ll try that
can I ask you how would I do that?
Research ethtool 
But of the top of my head something like:
ethtool -s wan speed 100 duplex full autoneg off
You might also need to disable EEE:
ethtool --set-eee wan eee off
happened again
root@OpenWrt:~# ethtool wan
Settings for wan:
Supported ports: [ TP MII ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Full
Supported pause frame use: Symmetric Receive-only
Supports auto-negotiation: Yes
Supported FEC modes: Not reported
Advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Full
Advertised pause frame use: Symmetric Receive-only
Advertised auto-negotiation: Yes
Advertised FEC modes: Not reported
Link partner advertised link modes: 10baseT/Half 10baseT/Full
Link partner advertised pause frame use: Symmetric Receive-only
Link partner advertised auto-negotiation: Yes
Link partner advertised FEC modes: Not reported
Speed: 10Mb/s
Duplex: Full
Auto-negotiation: on
master-slave cfg: preferred master
master-slave status: master
Port: Twisted Pair
PHYAD: 4
Transceiver: external
MDI-X: Unknown
Current message level: 0x000000ff (255)
drv probe link timer ifdown ifup rx_err tx_err
Link detected: yes
then run
root@OpenWrt:~# ethtool -s wan speed 100 duplex full autoneg off
root@OpenWrt:~# ethtool wan
Settings for wan:
Supported ports: [ TP MII ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Full
Supported pause frame use: Symmetric Receive-only
Supports auto-negotiation: Yes
Supported FEC modes: Not reported
Advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Full
Advertised pause frame use: Symmetric Receive-only
Advertised auto-negotiation: No
Advertised FEC modes: Not reported
Speed: 100Mb/s
Duplex: Full
Auto-negotiation: off
master-slave cfg: preferred master
master-slave status: master
Port: Twisted Pair
PHYAD: 4
Transceiver: external
MDI-X: Unknown
Current message level: 0x000000ff (255)
drv probe link timer ifdown ifup rx_err tx_err
Link detected: yes
but nothing changed, speed is still capped at 10Mbps, even after restarting the wan interface from luci. Also
root@OpenWrt:~# ethtool --set-eee wan eee off
netlink error: Not supported
Maybe the issue is with the radios? maybe both?