Help! Xiaomi mi 8 dual sim internet not working

[Kelpshark]

Hi, new to this forum.

Maybe someone has an idea how to fix this:

Mobile data sim in my xiaomi mi 8 does not receive internet connectivity but it works just fine in other devices. Tried everything including change apns, reset phone, change sim card slots...

It sometimes works for a short while when phone rebooted. Was perfect about a month ago.

Your help is appreciated!

Thank you.

 

[Don Henry]

I am also having (massive) difficulties with Dual Sim performance.
Apart from a very nice and interessting discussion with another member, I received NO answer, NO comment and NO help from the so called 'developers'.

By now, I also realized that even with only 1 sim card, the Mi8 has a lousy antenna and bad signal reception as well as signal management when moving. An old and very cheap LG has a super strong LTE signal, where and when the Mi8 is 'on and off' with a weak signal. (Same sim Card and exact same Position.)

Thanks to the input from this friendly member, I am convinced that all this is due to firmware problems. I tried flashing different fw versions and could see differences, but nothing really solved the issues to a satisfactory level that I am expecting from a flagship modell.

 

[cobben]

There is unfortunately always the possibilty that you have a hardware problem.

I just read somewhere that a common oldage problem with non-waterproof phones used continuously in a harsh environment (e.g. near near Baltic sea?) is oxidized antennas.

How you can check that without specialized knowledge and equipment I have no idea.

Here it is:

Fix unusual weak wifi signal power
https://forum.xda-developers.com/ga...-unusual-weak-wifi-signal-power-dain-t3873935

"Also the left and right top is mobile antenna. burnish it to shining also get a better signal and power save. "

 

[Don Henry]

Fortunately, my Mi8 hasn't seen the sea yet ;-)
The phone is obviously only a few weeks old, and always sat in a protective rubber case.
There cannot be any corrosion inside, yet.
(And the chance to break the rear glass cover of the Mi8 - while opening it - is quite high. Luckily, we can purchase a new back cover plus a specially designed adhesive sticker frame for it for under $ 20 incl. shipping from China. For this kind of glas covers you always need to heat up the cover to losen the adhesive beneath it, e.g. by using a hair dryer and HAVE LOT'S OF PATIENCE during the whole process.)

However, the old LG phone has been abroad and around many times. It's also meant to be opened as it has an exchangeable battery. And that's how you insert a sim card and a micro SD card. Despite having seen Thai rainstorms, the Adaman Sea and lots of moisture, it has also no corrosion

 

[cobben]

But if you have the same symptoms, you might have a faulty antenna even in a new phone, or one that was not fully/correctly attached in the factory.

 

[Kelpshark]

Thanks for your replies. Seems like there is not much that can be done

 

[cobben]

Thanks for your replies. Seems like there is not much that can be done

Have you tried a new simcard from your operator?

We have had some really weird problems through the years that have ben solved by getting a new sim card.

One girl in the Bite shop in Latvia took one look at our sim card, which worked fine in my wifes old phone, but not at all in her new one, and said:

"It's scratched the wrong way. It can be scratched this way, but not that way."

A new sim card worked directly.

 

[Kelpshark]

Hi, yes! Have tried that too since I have two different sim cards and the one in my phone is new.

 

[cobben]

Sim cards contain a microprocessor and a minimal os, that connects the units baseband system to the operators network. I only recently found that out.

So there are lots of possibilities for problems here.

I have a similar ongoing problem with a new router, where two different new simcards from one particular operator cause the router to constantly reboot, but work otherwise.

Both the router and these two simcards work flawlessly with other simcards/phones.

No-one wants to "own" this problem, as you can imagine.

In the end, the only reasonable solution is to dump either the router, that particular operator - or both!

 

[Kelpshark]

It must be something to do with the operator's sim card os is as you say. They work fine in a mobile router and the mobile internet works fine in both sim card slots for the sim card I have of the other operator. The frustration lies in the fact that I specifically bought this phone to use that operators offering as it is the cheapest in South Africa!

Looks like my best bet is to try another operator.

Thanks for your response.

 

[Don Henry]

Alright then

I just odered a new simcard from my operator.
Should be here next Wednesday.
I'll update you on the results ...

 

[Kelpshark]

Awesome, thanks

 

[Don Henry]

..in the meantime, you might want to try this rom:
ht tps:// mi- globe. com/rom-builder-features/?codename= dipper&img=mi8.png&realname=Mi+8
(remove the 5 space tabs in the above link)

It works a bit better for me than the eu.community's roms...

Enable expert settings and chose your option, i.e. GPS location --> Afrika ... and so on

 

[Don Henry]

Hey cobben & Kelpchark,

Even without the new simcard arriving in 3 days time, my Mi8 all of a sudden works like it should.
So much to the roms of this forum :-(
With the rom/link I posted above the sim card's and the dual sim cards' performance are just fine.
Good night & enjoy the remaining Advent weeks until Xmas.

Cheers
Henning

P.S. I will still update you on any (further) improvements wit the new sim card once it's arrived.

 

[cobben]

You do realize that the mi- globe roms are made directly from the Xiaomi.eu roms?

Why it would work better is an interesting question.

 

[Don Henry]

This is what they say on their website:
"Along with other software, apps and firmware modifications, on mi -globe. com we provide a complete ROM called “globeROM“, which is based on the official Xiaomi MIUI firmware. According to the official Xiaomi update plan, we always provide the latest stable or weekly developer firmware versions on our website!

I believe it's based on this one:
http://en.miui.com/download-346.html

The eu.roms are probably also made from the same one.
And I have no idea what they do differently, but as a matter of fact, the phone is finally performing as a phone

 

[Don Henry]

As soon as the phone is jumping onto Band 1 or Band 3 instead of Band 20 the performance goes down the drain again.
When the phone is connected via Band 20 everything is fine... But it switches back ti Band 1 or 3 randomly, even while sitting in the spot on my desk.
Do you know how I could somehow 'lock' the Band to 20 (800 MHz)
--> Modem/Transceiver problem and hence firmware issue ?

 

[Don Henry]

Hi Kelpshark,

the new sim card arrived today.
Got it registered, and it jumped onto band 20. Everything looked fine for 2 or 3 minutes.
Unfortunately, it then jumped back to band 3, and hence my issue wasn't caused by the old sim card.
So, yes, it might still be a (general) operator problem, a hardware issue or ... the firmware.
Hence, I cannot help you and meself :-(

 

[Kelpshark]

Sorry about that, good to know.

 

[Kelpshark]

@Don Henry hi again, so does your mi 8 work now with the global rom?

 

[Don Henry]

Yep, it kinda works.
But I am still not happy with the reliability and stability of the network signal performance.