AirMaster 4000D - disconnects for a couple hours but mostly works well

[chazz]

I purchased an AirMaster 4000D (technically in the "antennas" section of the site) for my Sprint service and 90% of the time it works flawlessly, with good signal, reliability and speed. However, roughly once a day, for an hour or two a day, it'll just start dropping the LTE link. Rebooting brings it back for a while and then maybe it'll drop again, maybe not.

But eventually it'll stop dropping connections and work properly again.

Is there a problem with the device, the tower, or what? I can't look at the network status page on the modem, it seems to crash and/or stop responding when I try, so I don't know what useful info it might provide. Most of the time it's at ~50-60% link quality, with 4-5 signal strength on the device's 5 LEDs. I have a tower that's probably a half a mile away that I point it at.

It doesn't seem to coincide with any power line noise or anything like that.

Any ideas?

[terryjett]

I am having pretty much same issue. Only difference once I reboot (unplug POE) seems to solve for the day. Seems to have started when T-Mobile started "tweaking" Sprint towers. Was wondering myself if equipment issues but your post got me thinking...

Are you in a hot climate? Airmaster mounted inside or outside? I ask wondering if getting too hot.

FYI: sometimes removing / reinserting the SIM card can solve strange issues. There are metal contacts touching the SIM card (metal too) and they can built up a film (oxidation). Heat can cause strange issues.

[chazz]

Not in a hot climate, and it is indoors. Temperatures maybe getting up to 75-80F the last few days. I only started using it a couple weeks ago, so I doubt it's SIM contact oxidation.

[terryjett]

Ok. But you may try to remove and reinsert the SIM card. One never knows the outcome until they do some troubleshooting:)

[Didneywhorl]

You may want to check the power source and the cables. Maybe for giggles replace the power supply, or poe source. Replace the LAN cable running to it, etc. One item at a time.

[chazz]

I ordered a replacement POE injector, but it won't show up for a few days.

It may be happening when it's warmer, I'm not sure exactly... it's happened twice today so far, once at about 5:30pm and at 6pm. At the 5:30 disconnect, it apparently rebooted since the uptime counter was reset. The 6pm drop did not reset the uptime. The device often stops responding to web admin connections or pings when it's malfunctioning. It definitely drops the LTE connection, but I'm unsure if that's just due to rebooting...

I reseated the SIM and it makes no difference. Also I don't think a SIM card connection issue would knock the device out completely. The cables I'll try replacing, but they are new Cat6E cables that I got specifically for this device.

[chazz]

Also my router says the ethernet link went down... which would in fact suggest that it could be the POE injector messing up. I'm not sure if it functions as a bridge/switch or what, but the physical link is, I'm pretty sure, negotiated by the POE device.

Hopefully the new injector will get here soon.

[terryjett]

Also my router says the ethernet link went down... which would in fact suggest that it could be the POE injector messing up. I'm not sure if it functions as a bridge/switch or what, but the physical link is, I'm pretty sure, negotiated by the POE device.

Hopefully the new injector will get here soon.

Good thinking and troubleshooting! Also make sure your ethernet cable is of high quality and shielded. I use a flat 50 footer but they also have a 25 footer https://amzn.to/3gRcCWM Just all depends on how far your antennas is from POE

Please do let us know the outcome, always interested in others findings.

[chazz]

Nevermind, the POE injector does not handle the ethernet negotiation at all. It literally is a passthrough that adds power, so the interface disconnecting could be anything. It could be my router, the injector, or the LTE device. I tried removing just the POE side and lost the ethernet link on the router, meaning it's a dumb passthrough device.

I have less hope for the new injector fixing my problem. Now I have to suspect everything... most of the time the AirMaster does not reboot, it stays connected to LTE (according to its LTE connection uptime) and the ethernet link goes down (according to the router log). It only fails for something like 20-30 seconds, so I never have time to check and see what the devices are doing.

Also today is much cooler and the problem is still occurring. I've tried replacing the cables now, so we'll see how that goes.

[chazz]

Ok, for an update... I have enabled telnet on the AirMaster and will be checking the dmesg output after any outages. If you have one of these, enable telnet through the web config (management), enable local access, and log in to its IP (same as used for the web config, 192.168.0.1 in my case) with a telnet client using user:root and pass:root123

If I'm really lucky, replacing the cables will have fixed it, but I doubt it. If not, hopefully the dmesg output will be helpful for diagnostics.

[chazz]

It behaves very strangely. Sometimes it reboots, sometimes it doesn't. Sometimes I can access its web interface, but when it malfunctions, I can't. It often drops the connection, and sometimes will reconnect on its own, and sometimes has to be rebooted. I'm worried that I have a bad AirMaster. I'll see what the new injector does tomorrow/when it comes, but it's not looking good. If I needed to exchange it, how do I go about that?

[terryjett]

Ok, for an update... I have enabled telnet on the AirMaster and will be checking the dmesg output after any outages. If you have one of these, enable telnet through the web config (management), enable local access, and log in to its IP (same as used for the web config, 192.168.0.1 in my case) with a telnet client using user:root and pass:root123

If I'm really lucky, replacing the cables will have fixed it, but I doubt it. If not, hopefully the dmesg output will be helpful for diagnostics.

More great info! I have never dug deep enough to discover the telnet settings. Will have to do some exploring.

I have a couple of the airmasters. First one connected up like a breeze after getting settings correct. Solid as a rock for months - until week or so ago.

The second one I had some issues with and was using brand new 50ft cat7e cable from bestbuy. Messed with it for week and decided to order new cat7e cable. Installed and never had any issues for few months - until t-moibile started combining our local sprint / t-,mobile towers. I now experience times of disconnects at random. In my thinking, all was good until we got text message week or so back on our t-mobile phones stating that local work was in progress.

Maybe their "work" has absolutely nothing to do with my disconnects but all was good up until that work began.

Big difference between yours and mine though. My disconnects seem to only a 20 seconds to maybe 2 minutes.

[chazz]

I replaced the POE injector and it seemed like it may have fixed it, but the stupid AirMaster just rebooted, so it's not fixed.

This sporadic rebooting and locking up is not acceptable. I think I need to RMA the thing and maybe get a replacement.

[BillA]

I replaced the POE injector and it seemed like it may have fixed it, but the stupid AirMaster just rebooted, so it's not fixed.

This sporadic rebooting and locking up is not acceptable. I think I need to RMA the thing and maybe get a replacement.

Most rebooting issues are caused by the lack of power (amerage) in 99% of cases. As a test you could try powering the router directly with a good power adapter, and if it's still rebooting then it's pretty safe to say that you have a defective unit. On the other hand if it works properly, then it's pointing to a POE power issue. Some POE units are simply unable to deliver the proper power, regardless what their label shows due to a significant power drop in long cable runs.
As a workaround you could increase the voltage from 12V to 16 or whatever the next step up is, which would increase the power delivery, just make sure you don't fry your device.

[chazz]

This device only has a POE power supply, no other jacks. I have tried 2 different POE injectors, one rated for .4A (the one included with the device) and one for .5A that I purchased separately, and neither fixed it.

I RMA'd the AirMaster and the replacement, so far, has only rebooted on its own once in a 48 hour period. The old one was rebooting and/or disconnecting many times a day. Hopefully it will continue to perform well, but only time will tell.

[chazz]

Replacement has now had a connection and device uptime of over 72 hours. I think the problem is solved, and that the previous device was just faulty. Some days it would disconnect and/or reboot 10-20+ times a day.

Speed and signal strength still vary quite a bit, but I think that has more to do with the weather/humidity where I am than anything. Also, temperatures have been pretty low for several days, but I doubt high temperatures were the problem.

Fingers crossed that it continues working well.

[terryjett]

Glad you got the disconnects solved. Surprised that the until was faulty since very well made but it can happen to any equipment.

With the high frequency of band 41 not unusual for signals to vary. I am one mile from tower with some trees in between and my signal varies with time of day.

[chazz]

Update on a somewhat old post...
So my Airmaster4000d stopped connecting completely. It says the sim is good, I still have an active LTE account, it sees the tower but does not register with it. I'm not sure what has gone wrong but it's very frustrating and I have no idea who to contact about it.

I don't think Pcsforpeople has a tech support...

Any ideas?

[terryjett]

Chances are T-Mobile has been "tweaking" band 41 for their 5G venture.

I have heard of pcsforpeople users contacting sprint directly. With all the changes with the merger, it is damn near impossible to get a straight answer. If you do call sprint, you may mention that you have been using band 41 and it stopped working all of sudden.

Another thing to try is put the sim in another device that is capable of other bands. The airmaster is band 41 only.

Just kind of a hit and miss with sprint support these days. I needed a sprint phone unlocked and it took 5 calls until I found someone who would do it.

[Didneywhorl]

I can confirm as well. Band 41, 25, and 26 in some areas are straight GONE, or neutered. It may come back, but Tmobile is wreaking havoc on the Sprint networks. You should get on Sprints online chat feature for tech support and ask for the status of your tower.

[BillA]

I can confirm as well. Band 41, 25, and 26 in some areas are straight GONE, or neutered. It may come back, but Tmobile is wreaking havoc on the Sprint networks. You should get on Sprints online chat feature for tech support and ask for the status of your tower.

I can confirm that today when I locked both my modem and phone to band 41 on Tmobile/Simple, it has finally connected for the first time. Not the greatest speeds even with 20Mhz bandwidth at my location, but hey, at least it's one more band to bang on Tmobile/Simple. ;D
By the way, when I locked it to bands 25 and 26 separately, neither one connected, guess Tmobile is reserving them for their legacy Sprint customers, and maybe will reuse them eventually.


Here's a list of all US 4G-LTE and 5G bands.

US 4G-LTE bands ("*" = Primary bands)
ATT = *2, 4, 5, 12, 14, 17, 29, 30, 46, 66
TMO = 2, *4, 5, 12, 46, 66, 71
VZW = 2, 4, 5, *13, 66
SPR = *25, 26, 41

US 5G-NR Bands/(frequencies)
sub-6Ghz is used primarily by ATT and Tmobile (bands are designated by the lower case letter "n")
n2 (1,900Mhz), n5 (850MHz), *n41 (2,500MHz), n66 (AWS-3), *n71 (600MHz)

mmWave is used primarily by Verizon (bands are designated by the upper case letter "N")
N260 (39GHz), N261 (28GHz)

[shoulin333]

I'm gutting mine and as it turns out the holes inside that hold in the PCB happen to exactly line up with two of the holes on the WE826-T2.

I have a EM7511 in it for band 41. Waiting on a POE bulkhead ethernet and 2.1mm splitter to get her from The Wireless Haven as well as a 2.1mm right angle adapter and a TS9 (female?) (end that would normally be in a hotspot) to SMA adapter. The panel antenna has TS9 connectors.

I will post more once I get it all together.

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[Didneywhorl]

Very cool!

[terryjett]

I'm gutting mine and as it turns out the holes inside that hold in the PCB happen to exactly line up with two of the holes on the WE826-T2.

I have a EM7511 in it for band 41. Waiting on a POE bulkhead ethernet and 2.1mm splitter to get her from The Wireless Haven as well as a 2.1mm right angle adapter and a TS9 (female?) (end that would normally be in a hotspot) to SMA adapter. The panel antenna has TS9 connectors.

I will post more once I get it all together.

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You did what I have wanted to do, just did not have the resources to invest in another project. I tip my hat at your ingenuity.

The antenna in the airmaster is top notch and very well engineered. Have made a few prototypes based on their design