Asus RT-AC1750 B1 Stops Transmitting 5Ghz Wifi

[dwp]

I have had an Asus RT-AC1750 B1 on standard AsusWRT 3.0.0.4.386_51733 running at a friend's house for many months now. Until last night it has been working quite well and devices connected to both 2.4 and 5Ghz without troubles.

I have no idea what happened but suddenly there was a loss of all connectivity and my friend, quite reasonably, powered off both his cable modem and the router. After powering on the cable modem then the router, connectivity was restored. However, there is no 5Ghz wifi available. I have looked for using both a Samsung S22 and a Windows 10 laptop (both of which previously connected via 5Ghz without problems). The 5Ghz SSID (same as the 2.4 but with 5G appended) is simply not showing.

I checked the router's settings via the web interface and all seems fine. I tried toggling the 5Ghz radio off and back on. I tried rebooting the router. Nothing has brought back the 5Ghz that was previously just fine!

I hope that someone can suggest what to do in order to re-establish the 5Ghz signal.

Thanks

 

[ColinTaylor]

Probably a hardware failure.

If you go to System Log - Wireless Log do you see the 5GHz band there?

 

[dwp]

Probably a hardware failure.

If you go to System Log - Wireless Log do you see the 5GHz band there?

I am not sure. I definitely see the 2.4Ghz. So maybe not in there.

I am supposing it might be a hardware failure of some sort. It just seems so odd that it should happen so suddenly and that the 2.4Ghz is fine. Thanks

 

[ColinTaylor]

I had a similar (but not exactly the same) hardware failure recently on my RT-AC68U, which is from the same era as your router. Basically, they're getting old now and prone the failures.

You could try doing a factory reset. If that doesn't help then post the System Log - General Log and System Log - Wireless Log for us to look at.

 

[Tech9]

I am not sure. I definitely see the 2.4Ghz.

The radios have their own hardware with separate power circuits, ICs and power amps. One of them failing is the most common situation. This router model (also known as RT-AC66U B1) has 2x BCM4360 inside in 2.4GHz b/g/n and 5GHz an/ac configuration.

 

[dwp]

The radios have their own hardware with separate power circuits, ICs and power amps. One of them failing is the most common situation. This router model (also known as RT-AC66U B1) has 2x BCM4360 inside in 2.4GHz b/g/n and 5GHz an/ac configuration.

Well, that helps me understand this a bit.

I definitely see the 5Ghz reported in the wifi log:

SSID: "0016014C2FXX-5G"
noise: -92 dBm Channel: 153
BSSID: D0:17:C2:58:62:XX Capability: ESS RRM
Supported Rates: [ 6(b) 9 12(b) 18 24(b) 36 48 54 ]
VHT Capable:
Chanspec: 5GHz channel 153 20MHz (0xd099)
Primary channel: 153
HT Capabilities:
Supported HT MCS : 0-23
VHT Capabilities:
Supported VHT (tx) Rates:
NSS: 1 MCS: 0-9
NSS: 2 MCS: 0-9
NSS: 3 MCS: 0-9
Supported VHT (rx) Rates:
NSS: 1 MCS: 0-9
NSS: 2 MCS: 0-9
NSS: 3 MCS: 0-9

Interference Level: Acceptable

But no devices see it. And, as you can see, none are connected to it.

I tried changing channel to 36 from 153 and no difference at all.

The radio is definitely enabled. The SSID is NOT hidden. Both 2.4 and 5Ghz LEDs are lit.

Measured all around the case with an IR thermometer. 90F to 102F depending where you measure. This seems more warm than other routers I have measured. But not sure about this unit.

Thanks

PS - I have complete sys and wifi logs. Not sure what I might look for in them other than what I show above.

 

[ColinTaylor]

Well, that helps me understand this a bit.

I definitely see the 5Ghz reported in the wifi log:

SSID: "0016014C2FXX-5G"
noise: -92 dBm Channel: 153
BSSID: D0:17:C2:58:62:XX Capability: ESS RRM
Supported Rates: [ 6(b) 9 12(b) 18 24(b) 36 48 54 ]
VHT Capable:
Chanspec: 5GHz channel 153 20MHz (0xd099)
Primary channel: 153
HT Capabilities:
Supported HT MCS : 0-23
VHT Capabilities:
Supported VHT (tx) Rates:
NSS: 1 MCS: 0-9
NSS: 2 MCS: 0-9
NSS: 3 MCS: 0-9
Supported VHT (rx) Rates:
NSS: 1 MCS: 0-9
NSS: 2 MCS: 0-9
NSS: 3 MCS: 0-9

Interference Level: Acceptable

But no devices see it. And, as you can see, none are connected to it.

I tried changing channel to 36 from 153 and no difference at all.

The radio is definitely enabled. The SSID is NOT hidden. Both 2.4 and 5Ghz LEDs are lit.

Measured all around the case with an IR thermometer. 90F to 102F depending where you measure. This seems more warm than other routers I have measured. But not sure about this unit.

Thanks

PS - I have complete sys and wifi logs. Not sure what I might look for in them other than what I show above.

Change to channel 36. Then take a phone running a Wi-Fi analyzer app, or a laptop, and place it right next to the router. Do you now detect the 5GHz signal, albeit very weakly?

 

[dwp]

Change to channel 36. Then take a phone running a Wi-Fi analyzer app, or a laptop, and place it right next to the router. Do you now detect the 5GHz signal, albeit very weakly?

I did try changing to 36 from 153 and that made no difference to the phone right in the same room (where it used to work on 153 just fine). Sadly, I am not there or could try the wifi analyzer on my phone. My friend is not too technical. Best

 

[ColinTaylor]

I did try changing to 36 from 153 and that made no difference to the phone right in the same room...

In my case the router's RF amplifiers stopped working. So the signal wasn't detectable even in the same room. By putting my laptop right up against the router I could just about detect (and connect to) the unamplified signal.

Your friend could try doing that if he's interested. But at the end of the day it still looks like a hardware failure of some sort.

 

[Tech9]

Most likely some soft of hardware issue. Replace the router.

 

[dwp]

In my case the router's RF amplifiers stopped working. So the signal wasn't detectable even in the same room. By putting my laptop right up against the router I could just about detect (and connect to) the unamplified signal.

Your friend could try doing that if he's interested. But at the end of the day it still looks like a hardware failure of some sort.

That is interesting as well. I will have him try it. It does seem that the router is having a severe hardware problem - although 2.4Ghz is working just fine. I handed my buddy the router after it was handed to me from another buddy. I have no idea about its history. It might have been surplused for this kind of problem and no one passed that along (or knew). I have a similar Asus CellSpot router I could configure and try. Best!

 

[dwp]

Most likely some soft of hardware issue. Replace the router.

Thanks. It is looking that way :-(