Default Problems with cellular and network signall cutt off.

I have my S4 2 weeks. And i have several issues with my S4. I'm from belgium and my operator is Base.

Sometimes it cuts automatically my cellular network offline.
Sometimes my network operator disappears till i reboot the device and after the reboot it remains offline for 10 to 45 minutes sometimes hours. so i can't get any calls or messages.

I get also allot of log sounds kinda notifications but none nofifications.
It also has some problems with my wifi on 2,4Ghz and 5,0Ghz to. Sometimes it cuts automatically off and needs to reconnect.
It's not my router it's the Asus rt-ac66u and brand new.

My smartphone info :

Model Nr. : GT-I9505
Android Version : 4.3
Baseband Version : I9505XXUEMKF
Kernel Version : 3.4.0-2082040
se.infra@R0210-18 #1
Wed Nov 27 22:04:32 KST 2013
Build Nr : JSS15J.I9505_4.3_0016
SE For Android Status:
Secure Boot Status : Type Samsung

Help me out? I don't know what to do. I heard from others that some people had a older baseband version and that they had not any problems with their S4.