Tested on xperia z c6603 [5.0.2][10.6.A.0.454]
You can check [5.1.1][10.7.A.0.222/228] Here

Pure stock kernel for unlocked bootloaders with

TWRP 2.8.6.0 or Philz 6.59.0 recovery.
Howto :

• Rename twrp/philz to boot.img and fastboot it to have stock kernel with TWRP
  fastboot flash boot boot.img
• To root, download Chainfires latest flashable zip from Here.
• Then reboot and press press volume up when blue LED turns on to enter TWRP/Philz recovery
• and flash the zip from the stored location.
• Unfortunately with stock corrupt deodex sony, we can’t instal xposed…

TWRP

• Backup stock rom usng pure stock kerne
• replace pure stock kerne with TWRP-v3.0.0-yuga.zip

Custom ROM

• Donwload Mokee android kitkat << bug
• cm-12-20150128-UNOFFICIAL-yuga
• Wipe all, flash it using twrp

Xposed

• Download xposed XposedInstaller_v2.6.1_by_SolarWarez_20151129.apk
• Instal as ussual

Constant Sign in to network notification

If you have problem like the title do this :

The steps:
1. You should be rooted
2. Install any terminal emulator
3. Run it
4. Enter su
5. press enter
6. Enter
settings put global captive_portal_detection_enabled 0
7. Press enter
8. Reboot