S5 G900F HSPA Data Network Error!!

Dear forum members!
1) I got S5 G900F Model with lollipop installed from my friend.
2) He give it to me because it will not receive WCDMA Signals at all. When it switches to WCDMA it will not capable to make voice calls and notification panel shows Emergency Calls Only.
3)It's fully functionalwith GSM Calls and EDGE data

It had G900FXXU1BOH4 Firmware !!!

Then i downgraded it to KitKat firmware version G900FXXU1ANE2_G900FODD1AND2

Now it works with GSM Calls, EDGE and with WCDMA But Only Calls in WCDMA mode.

It will get H+ Indication for few seconds but Never receives data. Browser shows up DNS Lookup error. But SIM is fully functional

So any Experts here to guide me right path???
Because i think it's messed with MODEM firmware or something.

OnePlus Two - HSPA+ and 3G Data Connection Problem

Hi Everyone,

I'm usually just a reader on XDA, but I have found a problem that appears not to have been solved and wondered if anyone had any insight.

Problem Summary
When in an area (or network) with only HSPA and UMTS (strong signal with no LTE or 2G available), the phone will drop from H+ to 3G erratically, always dropping the data connection. Traditional phone calls are not affected.

Detailed Description
I have a OnePlus Two and have 2 SIM cards. My first SIM Card is with Bell Canada (Virgin), and the second SIM Card is with WIND Mobile Canada.

Neither Bell nor WIND operate a 2G network, so the lowest the service can fall to is UMTS/3G.

Initially, I didn't notice the problem because Bell also operates an LTE network, and there is no problem with dropping the data connections when on LTE.

When I switched to the WIND SIM card (which only operates HSPA and LTE), I noticed a problem where the phone would initially connect to H+, begin downloading whatever is needed (say, streaming music), but then part way through the download, the connection would switch to 3G, and the data would effectively stop. Within a minute, the service would jump back to H+ and download some more, but this cycle would continue (H+ --> 3G --> H+ --> 3G... ), with no way of knowing 1) how long the H+ connection would last before dropping to 3G (usually less than 30 seconds), and 2) after dropping to 3G, how long before going back to H+. This problem makes the phone almost useless when there is no LTE.

The most obvious troubleshooting I did was move to locations of better signal but I quickly ruled that out, as nothing seems to remove this problem. Other things I tried was to: move locations in the city, reboot phone, hard reset phone, flash most updated version of Oxygen, unlock bootloader, root, try the HSPA Keepalive app, swap SIM1 to SIM2, and many other things.

I originally thought this was a network issue, but I put this WIND SIM in another phone and there was no problem in any way that resembled this problem.

I also ruled out this being a network-specific problem, as I have taken a trip with the Bell SIM to an area where Bell does not have any LTE coverage (only HSPA and UMTS) and the same problem occurs on Bell as with the WIND SIM.

I have found people who had this problem on the OnePlus One tend to recommend using 2G to stabilize the connection, but this is not possible on Bell or WIND. That solution also would not provide adequate data speeds.

Remember this problem only affects data connectivity, as 3G traditional phone calls have no problems.

Question
Does anyone know if there is a way to adjust the conditions when the OnePlus Two will choose to switch from H+ to 3G?

Does anyone have any easier suggestions?

Thank you all in advance, because this rendering this phone almost useless when there is no LTE coverage.