[Nexus 5 Q&A, Help & Troubleshooting] Will008:
I just want to write this post maybe it will help anyone that has or will have the same problem. I looked all over the internet and could not find a fix, so here is my fix. Hope it works.

I work over seas on oil rig sites (remote locations) so I talk to my wife and family back home via different VOIP apps so its important to get a 3G signal, usually I lock WCDMA only network and get at least 1 bar which is sufficient. All of a sudden I started experiencing very weak 3G signal on my phone, weirdly this was at the same location where it had full bars in the past. This only applies for 3G, I could get 2G signal no problem.

In other areas that I know had good 3G signals and towers were close, it would work alright outdoors but once I get behind a door or a window 3G disappears even if I have it locked. I put in my sim card in my old Galaxy Nexus and it had 3G indoors with no problems at the same place and right next to the N5. So I started testing with both phones right next to each other when I lock 3G with the same SIM the Galaxy nexus would get 3 bars while the Nexus 5 would get the empty triangle (emergency calls only).

I couldn't get out of my mind that I dropped my Nexus 5 a hard drop, but I have a rubber case that took all the shock and the phone didn't get a scratch on it. This was before the 3G signal starts getting funny. Couldn't help but feel that I broke it somehow though. I felt like this might have got something loose inside. What didn't make sense to me is that if the antenna didn't work it wouldn't get 3G at all, indoors and outdoors.

So Step 1, I assumed it was a software issue. I went through a painful hard reset. To my surprise it still had the same issue afterwards.

Then out of desperation I saw this dude's video on how he couldn't lock GPS until he opened the back of the phone and found that the GPS antenna was not connecting straight.

youtube com/watch?v=K1-uCIb-t8I[/url]

So I started searching for where the 3G or 2G antennas are on the N5, but couldnt find anything that points that out. The phone was worthless to me like that so... I took a deep breath and decided to open the phone. Keep in mind, i'm an oilfield engineer and I still had a feeling i might f@#k the phone up, specially that I did not have any tools with me.

So I watched this video on how to open up the back cover:

youtube com/watch?v=mkbmtu-1KSQ[/url]

and went through this guide on what's inside the N5:

theregister co uk/2013/11/05/nexus_5_teardown_shows_a_light_touch_thats_easy_to_fix/[/url]

Then I opened it, couldn't find anything to do, except maybe clean the minor dust off and blow on the ICs a bit. There is alot of pins that connect to antennas located on the back cover itself, so I closed it up, made sure its closed tight and all the pins touching, put in my SIM, and GOD DAMN!! IT WORKS AGAIN... I was getting full bars 3G!!!

So what I figured is that when I dropped it, one of those pins moved a little bit away and broke the connection between the antenna and the IC. Works great for the last 5 hours, solid connection.

Hope I would help anyone with this

PS: put the dots in the links, XDA won't let me post outside URLs