Yes, the same here. But I fear, right now, there's nothing we can do. I tried many elder modems but always same result: problems with booting, very laggy phone and loss of baseband, imei and so on. Only reflashing XXUGNG1 FW solved it (for me). Very sad thing. Such a great phone and so little mobile data receipt
Go to System settings -> More networks -> Mobile networks -> Network mode and change it to WCDMA only. Since it is more sensitive network type, It will hold signal better. You can make calls even when signal strenght is -101 dBm.
Since it is 4G network this sollution works only in places which are covered with 4G network GSM repeaters.
I hope that Samsung will solve this problem. I think that it is KitKat problem, more precisely, antenna power consuption is low so that battery would last longer.
If this helps you, feel free to thank me