App Store not working

Hi There,

I have an old ipad modell MD790SL/A with 12.5.7 software version. I did factory reset twice today and I signed in my apple id but appstore doesn't work. Internet connection (wifi) is working because I can browse any internet sites in the safari. I tried to sign in another apple id but the same situation. After that I signed in another iphone with my apple id and appstore is working. Can anybody to help me what the problem is? What can i do? Thanks in advance!