Slow 4G Play Store Download Speeds Fixed (kinda) - Verizon Samsung Galaxy S 4

Okay, so there have been a few of us who've been experiencing really terrible 4G download speeds, most notably so in the Play Store. I'm talking Kilobytes per second here, people. I could transcribe the code and compile it faster than this stuff is downloading.
Anyway, I believe I may have fixed the issue. I've rebooted a couple of times and my changes have persisted through, so I'm hopeful. My download speed went from being measured in KB to MB which made me feel like my phone wasn't trying to operate on dial-up with some free hours left over from one of the thousands of AOL free trials discs found laying about in the early 90's.
So, here's what I tried BEFORE my fix:
-- Various 3G/4G Speed/Network/Signal Optimizer/Fix/Strengthen/Repair apps on the Play Store. Two of those apps actually helped my download speeds for the first app I downloaded from the store; after that the speeds went right back to being dismal and embarrassing. Nothing else helped at all.
-- *#*#4636#*#* to Phone Information and toggled various network preferences. Nothing affected my download speeds.
-- Tried various Mobile Network options in the Settings menu. Nothing helped.
-- Toggled variations of Roaming modes, network types, etc.
-- Flashed back to stock.
-- Flashed to Slim Bean (what I was running before)
-- Tried dirty flashing over the roms after getting everything set up
-- Cleared Dalvik, Cache, Fixed Permissions
-- Completely wiped my entire phone and started from fresh
-- Tried custom kernels
-- Went to the Verizon store and got a brand new sim card
-- In Build.prop I changed ril.subscription.types from NV,RUIM to RUIM,NV. Some google search led me to a forum where someone suggested that. It didn't do anything for me.
-- In Build.prop I saw ro.product.locale.region was set to GB. Changed that to US and rebooted. No change.
Nothing I was doing was working. I was still getting the worst download speeds I've ever seen in my entire life. I swear to god I was getting better download speeds when I was like, 10 years old browsing the internet on a 14.4 modem on a 386 processor with Windows 3.11. I wanted to punch the internet in its e-face with my digital fist.
So, that's when I had a revelation. I just came from having a Razr Maxx that I'd flashed god knows how many different roms and kernels on over the course of the year that I'd owned it. I never had download issues with that, and it too was running on 4G LTE with a micro sim card in it. If that worked fine, then why doesn't this? With that question in mind, I remembered some of the settings I'd seen in the build.props over the past months and one of them stuck out as I was browsing the build.prop for my new SGS4:
ro.telephony.default_network
On this phone, it was set to 8, however I was 100% certain my Razr Maxx has that value as 14. I figured "screw it, let's give this a shot," and changed that value to 14 instead of 8.
When I rebooted my phone stuck at the Samsung boot logo. I had to pull the battery. I booted into recovery and decided to try something different than my usual "Welp this didn't work time to format everything and try again," approach. I wiped Cache, Dalvik, and Fixed Permissions then rebooted. The phone booted up like normal. I ran Speedtest to see if my speeds were still garbage or not. That test wasn't amazing by any stretch of the word. It was something like 6 mbps down, 6 mbps up. I was getting similar speeds before, so I wasn't hopeful. Then, I went to the Play Store "just to see," and downloaded a past purchase.
It started at 50kb and my heart immediately sank. Then, it went to 2 megs. 3.5. 6.2. 9. Download complete. I was hesitant to accept any actual change, so I downloaded another app. Same increased speed. I was happy, but reluctant. I rebooted, completely certain that my old speeds would return and I'd go back to contemplating a full factory wipe and attempt to return the device for another claiming it was defective. After the phone rebooted and obtained its data connection I went back to the store and downloaded another app. FAST SPEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEED!
I don't know what the heck changing that 8 to 14 did or what that value actually represents, but my speeds have remained "fixed". Granted, they're slower than they probably could be, but my Play Store downloads have gone back to acceptable rates so I figured sharing that information with you guys here might help at least one other person who can't understand for the life of them why their new phone refuses to go as fast as it should.
TL;DR: Went to Build.prop and changed ro.telephony.default_network to 14 instead of 8 and my Play Store download speeds went from kbps back to mbps.

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My issue has been very similar to yours. Except the only slow downloads I get are when they originate from Google. Running the speedtest app and viewing webpages all show my device is capable of downloading at serveral megs a second. But if I tried to watch videos on Youtube or listen to music I would get constant buffering and some downloads from the market (the more popular one like Angry Birds or Gmail) would only download at about 40k. Then all of a sudden everything started downloading at high speed again. I was overjoyed.
Today I decided to try another ROM and unfortunately after flashing some downloads are incredibly slow again.
I suspect that changing the default_network in the build.prop did not actually fix the issue you were having. Especially since the information I have found about the field suggests it sets your phone default network type to something like CDMA or LTE only after a factory reset of your phone. In any case I have set this same field to 14, cleared dalvik and cache, then fixed permissions and my download speeds remain just as slow.

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Well, I'm actually pretty confident it did because I was looking through apns-conf.xml and noticed that every instance of an LTE segment regardless of network (sprint, tmo, vzw) had this value
Code:
bearer="14"/>
. So, because of that, I'm pretty certain that the network type being set to 14 promotes LTE connectivity over whatever the 8 was, which is a value I can't find any reference for in this APN file.
You can try this, which is the actual steps taken for fixing my problem:
Settings -> More -> Mobile Networks
Data enabled [X]
Data roaming [ ]
National data roaming [ ]
Network Mode: LTE / CDMA / EvDo
System select: Home only
CDMA subscription: RUIM/SIM
Press Back, toggle Airplane Mode on then off
ROM Toolbox -> build.prop editor
ril.subscription.types RUIM,NV
ro.com.android.dataroaming false
ro.product.locale.language en
ro.product.locale.region US
ro.telephony.default_network 14
Reboot to recovery
Wipe Cache
Wipe Dalvik
Fix Permissions
Reboot

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What ROM are you currently running? At the moment I'm running stock and don't have the options for System Select and CDMA Subscription. I also dont have a ro.telephony.default_network entry in the build.prop.
Edited -> Added more information

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chronoquestion said:
What ROM are you currently running? At the moment I'm running stock and don't have the options for System Select and CDMA Subscription. I also dont have a ro.telephony.default_network entry in the build.prop.
Edited -> Added more information
Click to expand...
Click to collapse
I'm using Slim Bean.
If you're on Stock, you should be able to do this in Mobile Networks:
Mobile Data [X]
Global Data Roaming Access: Deny data roaming access
Network mode: LTE/CDMA
In ROM Toolbox Pro's build.prop editor I also saw that the region was set to GB. That should go back to US if you're in the US.
Edit: Actually, if you're on the stock rom you can go to Settings -> More -> About Phone - Status or whatever the option is. If you look for network type or connection type, you should see something like Verizon LTE 14 or something similar. That's the 14 I was talking about. If that says 14, you should be good.