Why is there no Internet through a router?

Good afternoon. A month ago I started to lose internet 10 times a day for a short period of time (3-5 minutes). I blamed it on the provider. The other day Wi-Fi disappeared and is not restored for about 3 days.

I plug the wire into my laptop – everything works fine. I plug it into the router – no internet. I have not changed any Settings in the computer or in the router. The router is already 5 years old ( d-link dir 615). I decided to change it, I thought it was the problem. I bought ASUS RT-N300, entered all the data from the contract (ip, gateway, dns, mask). The router worked for exactly a minute and a half. Then everything became the same as with the old one. Internet is not. What can be the problem?

Answer

Good day. “No wi-fi” and “No internet” – are different things. And since you confuse them (in the description of the question), it is impossible to understand what is going on there and what exactly is the problem. RT-N300 is not a router model.

Do the devices (different ones) not see the Wi-Fi network of D-Link and ASUS router at all?
Or do the devices see the wireless network, connect to it, but the Internet doesn’t work?
Is your ISP exactly using the Static IP connection type? Did you choose it in the ASUS router settings and specify all the necessary addresses?
Be sure to check with your provider if he/she does not bind by MAC-address. Because of this the Internet through the router may not work.
Pay attention to the WAN (Internet) indicator on the router case. Is it lit/blinking?

Please go through these points and complete your question in the comments. I will try to suggest something.