[G3 Q&A, Help & Troubleshooting] FierroGamer:
I'm making this thread as I have a very hard time trying to find a solution on my own, I've read from these forums a lot in the past but this is the first time I make an account and post something.

First the problem: I have bought an used LG G3 phone that was bought with my carrier (personal, is from Argentina), once I got home I only used it with wifi and then flashed fulmics 5 and updated it (since I've read a lot about the phone before buying and found that the stock rom is very bad with battery, plus I really liked the rom as far as I've seen about it) and then flashed it again because I didn't select the options I wanted the first time, in both cases I've wiped data and did just about everything indicated in different tutorials, I've used twrp for flashing. After all that I've asked for mobile configurations to my carrier and at the next day, I asked my old man (the line is at his name, because of employee discounts and all that) to activate LTE for my line (I've never had a phone with LTE and with my carrier that needs to be activated in the line) and after following indications such as rebooting the phone, I decided to test my mobile speeds with LTE and they were incredibly slow (under 0.05 Mbps both up and down) and today I checked again with full signal and had the same results (give or take a couple of bps), I also installed a new kernel called xceed and tried again with no change in results (I don't know if the kernel would affect this, but I mention it just in case), and since I had my parents around at the moment, I made them try (same plan, same carrier, diferent phones) and both got normal LTE speeds (20+Mbps down, up varied), the weird thing is that my speeds are about the same with 3G H+ while wifi works normally, mobile signals are normal, even getting full bar during some of the tests, I have double checked more than a few tiems and I have the apn correctly set and all that. I don't think it could be the SIM since I've been using it with fast 3g speeds in my moto G before without a problem, but I'm still going to request a new SIM to my carrier just in case.

Short version: I've got unde 0.05 MMbps up and down in LTE and HDSPA.

Specs and all that:

- LG G3 D855 16GB version

- Carrier: Personal (Argentina)

- Data plan: unlimited speed, 500MB at a time, refreshing costs part of my credit and I've checked, I haven't surpassed my data cap, I'm far from it.

- Software: Fulmics ROM 5.3 and xceed kernel running 6.0 Marshmallow

- Emotional state: mixed feelings, it sucks to not be able to use mobile internet and the poor battery life but at the same time this is my first high end phone and it feels awesome.

I hope someone can point me in the right direction as I'm lost like an old-timer in the dance floor.

Extra info: I'll try flashing the rom again, but I would like to try different solutions first, there are some things I don't like to set up over and over, plus I want to know what could be the reasons, the very few people I've found on the internet with the same problem (excluding people talking about carriers from the US) had a case of a bad SIM card.

UPDATE: well, this is awkward... it turns out it was my plan, I checked once again and my data had to be resetted, now it works, 6mbps down and 1.3mbps up, it's not as fast as it should be but it works now. Sorry for the useless post