Have internet access on desktop but wifi; limited.

Hi,

The internet access on my desktop is great, I mean it's quite fast and I can access any site. But when I am using my Android phone, I don't know if I can say it doesn't work cos it does, but... limited? I mean, I can use Kakaotalk and Viber. I received and can send messages through those applications but when I access some site using chrome mobile, it doesn't load. Sometimes it would say "no date receive" or sometimes it would say "DNS lookup failed".

I would stay calm if it's only with my phone, but all of the smartphones I've got are having the same problem.
Like, I don't have access to playstore, and so many more google apps. (MAIN PROBLEM)

I've checked my ethernet and it is up to date and I don't know what to do anymore. It feels like, I cannot use the wifi, or more like it became useless to me, or to us, since our devices won't connect properly to the internet.

I really need help :( My work involves using some apps in my mobile and wifi, I really need to fix this wifi issue.

Thanks in advance.

Regards,

Haru