[Samsung Galaxy S8+ Questions & Answers] link1981:
S8+ /S8 Global Unlocked Variants, (ie: G955FD, etc) Desperately need help w/issue After 8.0 Update...

Hi, I have a G955FD & have family members with this same model, as well as the Global unlocked regular S8-dual sim. We all have the same issue after the Samsung 8.0.0 update. The phone is no longer reliable. Randomly, these devices will not have any ring on incoming calls. If they don't leave a VM, then you have no indication of a missed phone call. In addition, random periods where text messages will also just not come thru. Difference on the texts is, when you reboot, they all populate in the message app and notifications. But the incoming calls are not known and lost forever w/o a VM left for you by caller.

I have been in contact with Samsung, although they indicate right off that I have no warranty because I didn't buy a carrier device from an authorized vendor for my local use, they were open & helpful to reveal that they are aware of '8.0 ringer issues' on the unlocked global devices. BTW, this must be a huge number of people across the world with this problem, but like my friends/family, originally think they have signal/carrier issues etc. Samsung says that it should be addressed in a patch or update..... but, WHEN? I have had a messed up phone for over 3months and counting.

The only thing that can be done to attempt having the phone work 'more often' is to do a restart every hour all day long and hope that your phone will ring when someone is calling.

I, personally, being the family tech guy, am the one working on the issue so I'm here to ask for help/input.

Been dealing with this issue for over 3 months now, here's some of what I have done and what I'd like help with please...

I have attempted 5x to install a custom ROM from XDA to alleviate this issue completely, but as of now, still unsuccessful. I've been rooting/hacking my android devices since my 1st but somehow can't get the process to work thru. At this point, using Odin, I have no issue to get my phone running TWRP and rooted. Somehow, after that point something isn't going right and my phone has to be re-odin flashed with OEM ROM and then wait 1 week for OEM unlock to re-appear to try again. So, If I could complete this process next time the OEM-unlock is back up, my problem would be over.

Now, since I am having issue with completing a custom ROM install... I thought, why not flash a previous OEM ROM (7.0 NOUGAT) and again, my problem should be over and I could wait until a 9.0 update to see how that goes. So far, any 7.0 stock ROMS I have been able to find/download, have 'failed' install in Odin. (I have standard Odin, patched and Prince Comsey) so I always try them all before I say it's a true fail.

Can anyone help me to understand why, with all the root/roms Ive done, cannot get custom ROM to complete install. I was trying for the CarHD or Batman. after rom flash, something goes wrong and the phone either goes bootloop or failed verify. (BTW, couple X I did flash the no-verify to alleviate that issue but still get bootloop or no new rom boot up)

The other thing I'd love to be able to do right now that 'should' be a piece of cake, (but hasn't been) until I figure out the custom rom install issue, is to ask for anyone that can post a link to a valid ODIN-flashable Stock 7.0 NOUGAT ROM for my S8+ G955F/FD. That would solve everything for now and I'd just disable updates for the interim. As previously mentioned, the couple I have found would only FAIL on Odin flash attempts. Seeing that this is a global, unlocked device, is it possible to flash a stock rom or flash a diff CSC that can get me North America Tmobile setup (my USA provider) I noticed that the global phone has no options to disable LTE or turn wifi calling on/off etc.

I apologize if I have jumped around in my post, not provided enough details or not written very eloquently, but I am happy to provide any other needed info to move forward if any of you have ideas here. I'm just at the end of my rope with this right now.

Any help, input here is much appreciated! TIA! mark~