quite a complex procedure you followed.. perhaps your device has a mismatch in the modem (radio) . I experienced similar signal drops and disconnections when I inadvertently upped to 442 (NC1) while keeping the MG1 modem..
Sent from my GT-I9505 using XDA Premium HD app
Certified Couch Tester
Current:Galaxy S5 XtreStoLite and Galaxy Tab 2 10.1; SlimKat
Past: Galaxy S4; Samy Deluxe Jelly Biafra
Nexus 4; Z1 ROM (xperia XL)
Galaxy S3; SlimKat
Galaxy S2; HellKat (Diablo kernel)