I'm on Telstra (which is the largest network provider in Australia) and I usually get full coverage but 2 weeks after getting my new LG G4, my reception keeps dropping out completely... it'll say I have 3 bars reception, but when I check network, it tells me I have -115dBm and if I try to make a call, it'll go from 3 bars to immediately nothing and then say "out of service area". If someone tries to call me, it'll get sent straight to my voicemail.
I've done all the normal troubleshooting, including a sim swap, as well as putting the sim in another phone (S4) and it works perfectly fine.
I think it's a phone issue, but nobody else seems to be having the same issue as I am or even similar...