[Galaxy Note 3 Q&A, Help & Troubleshooting] SilverHelmut:
Hi all,

Having a problem here.

Had my N9005 for about 18 months, never really had any problems with it - or rather, never really required anything of it which might manifest any problems.

I've always used Stock ROM's, soft-rooted.

Never triggered KNOX.

I'm currently running Stock Lollipop (latest Switzerland Open). Everything I'm about to elaborate is also the same using Stock Lollipop (latest UK Open).

I'm rooted on Lollipop using the method compiled by The TAMAS on XDADEV.

I root because my phone is work-critical, and so I use Titanium Backup to keep my data/calls/APN/SMS backed up and to make restoring easy, as well as to disable stock bloatware etc.

The problem may have pre-existed in pre-Lollipop ROM's, but the sequence of changes which caused it to be manifested included my need to update to Lollipop, about 5/6 months back.

THE PROBLEM - First and foremost, the damn phone reboots randomly. I become aware of it because it will vibrate for startup and play the Samsung startup tone and splash screen before booting to normal functionality. It can do this day or night, maybe 3-4 times a day. I have no error messages or warnings, it's done it while in my hand, while plugged in charging, while out and about, in the car, on wifi, on data. MOST times it reboots. SOME times it just shuts off and I don't realise it's off until I go to use it, or get a call on a second phone to ask why I'm not responding to calls or messages.

When it reboots itself, if I go to the Samsung Battery control panel pane and take a look at the battery chart it will show a gap which is longer than the time it took to reboot, and a shift in the battery meter level.

But, that's not the only possible symptom or problem with the phone.

I've noticed also that my WIFI does a lot of crapping out, or slowing to a crawl, even on my home AP. I've reset AP's, reset networks, reset the phone, forgotten and then reattached the AP in WiFi Settings. So I downloaded the Ookla Speedtest App, to see this issue in black and white, and sure enough, even though any other Android or iOS or Windows or OSX device in my place can connect via Wireless AP to my fibre connection and get great consistent throughput, the Note 3 can often appear crippled...

At it's best, it responds to ping quickly on the Speedtest app, and leaps up to the 30-40Mbps range with consistency for download, and up to 17-20Mbps for upload. This is the least I would expect it to do, my target standard.

At it's worst (which can be 'most of the time') it responds slowly to ping, and either struggles to get over 250Kbps download and maybe a crazy Meg or two for upload, consistently, a slow grind; or it may oscillate extremely wildly between slow and high speeds before eventually settling to unacceptably low transfer rates.

Up to press, I've been trying to chase these problems in isolation, believing them to be unconnected.

No success.

I've reflashed several times. I've Factory Reset. I've wiped data and cache. I've reinstalled and restored from Titanium. I've reinstalled and restored nothing but my SMS's and Call Logs. I've reduced my installed apps to bare minimums. I've tried it with a MicroSD installed, and without. I've bought another battery and replaced it. I've tried it in its case and without its case.

Then I started thinking that the problems were all the same thing, and stemming from the same root.

It suddenly occurred to me that my use of the phone changed significantly at the same time as I moved to Lollipop.

I need to be on Lollipop because apps and hardware that are critical to me are Lollipop dependent.

All at the same time, I began using a Moto360, a Bluetooth Receipt Printer and a Bluetooth Credit Card Reader, all of which are deficient in functionality or in some way hamstrung by not using Lollipop.

So I had gone from occasional BT user (maybe PlayerPro plus a BT link to headphones or my stereo occasionally; when needed, BT speakerphone in car) who usually turned BT off manually to preserve battery life, to a constantly connected BT user...

So I went back to Speedtest app, and tried to test the WIFI connection again. Sure enough, it was pitiful. Then I simply disabled BT on the N9005 and ran the test again, and had full 'through the roof' speed ratings.

I've tried this back and forth hundreds of times now, and it is predictable and established. BT is somehow crippling WIFI on my N9005.

I've tried running the phone on either wifi or data only, with BT off, and had a couple of days use at a time without any restarts. Put BT back on permanently, and the restarts resume within hours.

I'll be honest, I've even been cursing and swearing at my BT devices, because BT sometimes struggles to even maintain a continuous connection. I get vibrations all the time on my Moto360 indicating that the phone, which is on my person, has disconnected from the watch again, perhaps just for moments, sometimes for minutes, resulting in the watch eating battery life, trying to get reconnected.

I'm convinced now that all these things are related, and the problem lies somewhere in the interaction between BT and WIFI in my N9005.

It seems likely that I never noticed the problem before because I never required continuous BT connection before the point where I installed Lollipop.

Downgrading the ROM isn't an option. Leaving BT off isn't an option (nor should they have to be, on an 18 month old £600 smartphone).

Does anyone else have experience of this? Has anyone else had problems that they now suspect might be this same problem? Does anyone understand what's going on hardware/software wise, or have experience of a solution to these issues?

I'd appreciate your input urgently, even if only to affirm that I need to go to the inconvenience of temporarily buying another phone to replace this, while I send this away for a warranty repair.

Is this even a recognised hardware fault, or would I just get back an identical unit which is crippled from being able to perform as I expect it?

Please help.