The phone connects to Wi-Fi, but the Internet does not work. What action to take?

Question

Android

Hello, friends. I visited you many times and saw that the community is alive here and can give a normal, understandable and adequate answer (not like bots in Mail).
Let's get to the question, shall we? I will try to convey the details and essence of the issue as accurately as possible.
Phone Samsung GALAXY S 5 mini / Android 4.4.2 / From factory settings I was able to update once when I was with a friend |, connects to my Wi-Fi (as well as to everyone), but the Internet works everywhere except mine.
Router (ZyXEL). I rebooted, registered something there, etc., but there was no sense (most likely my jambs). What can I do to make the phone or router stop freaking out and give me the Internet?
And the second small question. Periodically on devices, the Internet is also cut down.
Phone: Samsung GALAXY S 5 mini/Android 4.4.2/ I was able to update from the factory settings once when I was with a friend|
Router: ZyXEL
OS: Windows 8.1
Like everything. I will be very glad if they give me help, and even better if it helps me. (as a beginner, can you write easier?)

Answer 1

Do other devices normally receive internet via wifi from your router?

Answer 2

Try changing the encryption settings in your Zixel, and also check how free wifi channels are (use WiFi Analyzer 4 android OS) and crawl to a freer one....