Z2 Wi-Fi 5GHz issue (missing channels/disappearing channels) - Xperia Z2 Q&A, Help & Troubleshooting

RIght, firstly I've got a UK Z2 (Vodafone model, but unlocked and subsequently flashed with a different ROM).
My problem is that I can't connect to a router that only operates on the following channels at 5GHz; 149. 153, 157, 161.
These are apparently valid in the UK, although my iMac won't see them - but it's a 2009 model. My MacBook Air (US import) does, and my Z1 Compact (with EU Generic ROM) does. So does my Xperia SP. The Z1 I recently sold did too.
Now I assumed that the UK ROM, and now my Taiwanese Z2 ROM (the router is Taiwanese too), supported it because when I turn on the phone, it can see the router. However, it can't connect. It never gets an IP address, and then soon after it disappears never to be seen again! That's unless I reboot, but even then - sometimes - it won't show then either.
The Wi-Fi signal is excellent.
I've read before (for the Xperia Z) that you need a SIM card inserted, and there is. It's a Three UK SIM. That perhaps tells the phone what channels to use? But if it thinks these channels are not allowed, why does it initially show the router? Is there a delay before it notices what can't be used? And why would one UK SIM hide the channels, but not another?
In any case, my Z1 Compact currently has no SIM card inserted but still works.
I'm very confused. It doesn't appear to be a hardware issue (it would be a weird problem if it was), so it must be down to the ROM - and I've had both .55 (Vodafone original and then a EU generic) and now the Taiwanese .69 ROM.
Sorry for the long post, but I wanted to try and pre-empt any questions that might get asked.
Basically, is anyone else having the same issue and does anyone know a potential solution? I can't change the channels on the router and there's no other firmware for it. Obviously I could change the router, but I think I'll just have to stick with 2.4GHz in that case.

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I know you say no fw is available for the router but im assuming you mean stock? Is dd-wrt/tomato available for it?
My s3 was the same on every custom rom i tried, 5ghz was always iffy :/ Will let you know if 5Ghz works for me when my z2 arrives friday

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5 ghz works for me but not using the mentioned channels, in fact my router Won't even allow me to use those channels.
Sent from my D6503 using Tapatalk

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corallus said:
5 ghz works for me but not using the mentioned channels, in fact my router Won't even allow me to use those channels.
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The thing is, the router is from Taiwan and there doesn't appear to be any way to change the channels it operates on. For 5GHz, those four channels are it.
They do appear to be legal in the UK, but many devices won't support them.
I am just confused as to why the channels work on the SP, Z and Z1 Compact but not the Z2. And even more confused because it will show up for a little while but not connect, then disappear. That's an odd way of restricting Wi-Fi channels on the part of the handset.

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Can you maybe doing a forget network and then re-adding it?
I'm in Singapore and have no problem connecting to 5Ghz channel 161.
I don't think it makes much sense for them to limit channels on the client side as people can travel anywhere with their smartphones and should be able to use any channel available..
Sent from my 2013023 using Tapatalk

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p4t4h said:
Can you maybe doing a forget network and then re-adding it?
I'm in Singapore and have no problem connecting to 5Ghz channel 161.
I don't think it makes much sense for them to limit channels on the client side as people can travel anywhere with their smartphones and should be able to use any channel available..
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Yes, but some devices do still restrict channels - based on what region you've set, and possibly in this case the SIM card.
I'll need to do further tests, like swapping the SIM for one, to see if that makes it work. At least then I might be in a position to report it as a bug to Sony.
I have removed/forgotten it when it was there, forcing me to re-enter the code, and it just doesn't connect. And while it isn't connected, it does then stop the phone connecting to anything else unless manually select it.

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whats the make/model of the router?
Can confirm 5Ghz works just fine for me using Doom's kernel and Aur

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jonmorris said:
RIght, firstly I've got a UK Z2 (Vodafone model, but unlocked and subsequently flashed with a different ROM).
My problem is that I can't connect to a router that only operates on the following channels at 5GHz; 149. 153, 157, 161.
These are apparently valid in the UK, although my iMac won't see them - but it's a 2009 model. My MacBook Air (US import) does, and my Z1 Compact (with EU Generic ROM) does. So does my Xperia SP. The Z1 I recently sold did too.
Now I assumed that the UK ROM, and now my Taiwanese Z2 ROM (the router is Taiwanese too), supported it because when I turn on the phone, it can see the router. However, it can't connect. It never gets an IP address, and then soon after it disappears never to be seen again! That's unless I reboot, but even then - sometimes - it won't show then either.
The Wi-Fi signal is excellent.
I've read before (for the Xperia Z) that you need a SIM card inserted, and there is. It's a Three UK SIM. That perhaps tells the phone what channels to use? But if it thinks these channels are not allowed, why does it initially show the router? Is there a delay before it notices what can't be used? And why would one UK SIM hide the channels, but not another?
In any case, my Z1 Compact currently has no SIM card inserted but still works.
I'm very confused. It doesn't appear to be a hardware issue (it would be a weird problem if it was), so it must be down to the ROM - and I've had both .55 (Vodafone original and then a EU generic) and now the Taiwanese .69 ROM.
Sorry for the long post, but I wanted to try and pre-empt any questions that might get asked.
Basically, is anyone else having the same issue and does anyone know a potential solution? I can't change the channels on the router and there's no other firmware for it. Obviously I could change the router, but I think I'll just have to stick with 2.4GHz in that case.
Click to expand...
Click to collapse
I previously owned a Z1 and found that 5ghz wifi was very poor on this device.....I now have a Z2 and the wifi is exactly the same.......works well on 2.4ghz, but poor on 5ghz. My wife's Nexus 5 works well on 5 Ghz so it must be down to Sony's implementation. I am using channels 36-48 not sure if I can access the higher channels, I presume not....think my router only has the lower channels......I have searched the web before for an answer to the problem, but no luck as yet....:crying:

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just to add my 2cents to this, My UK bt homehub doesn't have those higher 5Ghz channels highest is 128 lowest is 36

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Yeah, this has happened to me recently aswell. I used to connect the 5GHz 802.11ac wi-fi network at home on my Sony Xperia Z2, but a couple'o days ago it disappared. I can't see the 5GHz signal, I'm using 2.4GHz instead. But my laptop can see 5GHz signal and connect without any problems. The channels on 5GHz signal is 149,153 by the way. And channels 11, 7 on 2.4GHz signal.
So what might be the problem within my Sony Xperia Z2?
Thanks in advance.

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Oh I just relieved that this problem is not only for me... Okay as some people mentioned wifi for Z1 was poor and Z too... so it might be problem w/
design of Z series. I am using AC-7260 wlan for my PC　and seeing 5Ghz AP. But not for Z2.... 　
No jamming around my home, no one is using 5GHz other than my AP.

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My Z2 works excellent on my 5ghz channel. I'm on vacation now so can't verify the channel I used. What I do know, is certain devices don't work as advertised with 5ghz. Just because one device sees it doesn't mean every device will. I've had to switch channels a few times for different phones although my laptop has always seen it.

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Yeah, it must be the channel issue, I suppose. But at first, my Xperia Z2 was connecting to 5GHz signal without a problem... After a while this issue started. I didn't change any channels or something on my router, either. Interesting...

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5GHz signals have inherently smaller ranges than 2.4GHz ones.
That said, my Z2 connects to my 5Ghz AC network just fine (range sucks though) but it has a problem keeping the connection to the 2.4GHz N/Mixed network from the same router (dualband ASUS RT-AC66U) alive after a period of time. It will still show as connected (with good signal strength) but will not have any access to anything else.

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benengyj said:
5GHz signals have inherently smaller ranges than 2.4GHz ones.
That said, my Z2 connects to my 5Ghz AC network just fine (range sucks though) but it has a problem keeping the connection to the 2.4GHz N/Mixed network from the same router (dualband ASUS RT-AC66U) alive after a period of time. It will still show as connected (with good signal strength) but will not have any access to anything else.
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Yeah, I'm well aware of this range thing between two signals. But my problem isn't something about it. My phone used to see and connect 5 GHz signal, but it doesn't see 5 GHz signal at all now. Even when I put my phone right on the router, between 6 antennae. (3 x 2.4GHz, 3 x 5GHz antenna)
This must either a software issue, or channels on 5GHz signal... But no, my phone was connecting without any problems for 3 weeks with the same channels. Must be software.
This isn't my only problem with wifi anyway, there's also a Bluetooth interference with 2.4GHz signal. Happens when Bluetooth is on at the same time with wifi. And when connected 2.4GHz signal, connection drops sometimes.

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i found this thread now i had posted one earlier today.
what I have figured out is - the moment the SIM is inserted Z2 is taking off the channels that are not "legal" possible in the country determined by SIM.
I am on Telkomsel - indonesia, if NO SIM - I am able to connect on 5 GHZ very well. but once it senses the SIM card, the 5 GHZ vanishes.
This never happend on Z Ultra!
next step is to test on other channels on the router in 5 GHZ to see if it is limitation of Z2. Right now my router supports only 4 channels - 36 40 44 48 on 5 ghz band.
otherwise my mac and other units connect and work pretty well on these channels!

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Alright, I've had my Xperia Z2 for 3 months now. I've never connected to my 5 GHz 802.11ac signal before, the phone doesn't detect it. I can only connect via 2.4 GHz band.
Why my phone doesn't detect 5 GHz wifi signal? What's wrong? What do you suggest?

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What ia the max link speed you get on 5ghz in z1 compact

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I don't know if anyone with a Z2 still has this problem, but I did and I seem to have fixed it by not setting my router to VHT80, but to HT40 instead. As a side note, my Chromecast seems to be able to connect to it now, too. My router is a Netgear Nighthawk (R7000) running the latest DD-WRT Kong Mod.