[Lazar 61]

My Lumia is 640 xl ds
I've tried a few times to install w10m, .29, .36, .63, and phone DO NOT WORK! It is hot, battery drains quick, too many blue dots and waiting between apps, random restarts, call drops, . . . in short, the phone is not usable. My wife's phone (lumia 640 LTE is on .71 and works as a charm. I have made both upgrades (on similar ways). LTE Lumia was made for Polish T-Mobile, bought in Serbia as unlocked phone, and xl ds was bought as operator free, European version in Serbia too. First, before upgrade I must uninstall all keyboards except English, or I will have no keyboard under w10m!. Under fast ring installs .29 first and then goes to .36. . . but phone gets hot and not responding. This is the second time I write about this, and it seems windows crew does not care for me after I spent my money, buying TWO windows phone! This is not nice! So please help!

[Chintan Gohel]

My Lumia is 640 xl ds
I've tried a few times to install w10m, .29, .36, .63, and phone DO NOT WORK! It is hot, battery drains quick, too many blue dots and waiting between apps, random restarts, call drops, . . . in short, the phone is not usable. My wife's phone (lumia 640 LTE is on .71 and works as a charm. I have made both upgrades (on similar ways). LTE Lumia was made for Polish T-Mobile, bought in Serbia as unlocked phone, and xl ds was bought as operator free, European version in Serbia too. First, before upgrade I must uninstall all keyboards except English, or I will have no keyboard under w10m!. Under fast ring installs .29 first and then goes to .36. . . but phone gets hot and not responding. This is the second time I write about this, and it seems windows crew does not care for me after I spent my money, buying TWO windows phone! This is not nice! So please help!

what does the ds stand for?

If at this stage your phone cannot handle windows 10 mobile, then you're advised to stick to 8.1 until sometime in the future.

After installing W10M, you have to let it update apps and sync content. This takes time and uses a lot of data hence the phone will get hot. Give it time to finish the process and then after all apps have updated and content has synced, do a soft reset. If phones still has bugs, then do a hard reset

Installing W10M insider is a risk that you willingly take, the sellers of the phone did not say you have to update to W10M

[Somchai Quint]

I also use a Lumia 640 XL and the first thing I did after unpacking was installing windows 10 mobile through the insider fast track. My Phone is running without any major Problems. Battery Life is fine, never get hot.

[Rugish Dapeca]

what does the ds stand for?

Dual SIM

[AOFSOCAL]

I'm running build .71 on my Lumia 640XL firmware version ...35003. I believe the phone is the Asian version and is DS and unlocked.

I am running this version from the Fast Ring and after the last update did not restore from a backup. The firmware has been stable enough to use as my daily phone. What i did was set the location for apps on the phone and music/video/pictures on the SD card. I rarely have gotten an app crashes or reboots Battery life on this build feels slightly better than the previous Insider build which was quite good. I also have very few apps installed (just because I don't use a ton of apps).

So some suggestions:

Reset back to stock .71 firmware.
Don't restore from backup set it up as a new phone.
Install apps on the device, media on the SD card (if you have one).

From one 640XL owner to another, good luck. It really is a fine device