Why is the internet going down?

Question

ZyXEL

We have:
Grid, 25 people, cisco switch, connected to the cisco asa5505 screen, which, in turn, to the zyxel 600 series modem, further to the Internet, connection in bridge mode.
the situation is as follows:
It started from 2 weeks somewhere:
the Internet disappears every hour, it happens every half an hour, it disappears and appears after 3-4 minutes, I looked at the modem, the dsl indicators go out for a few seconds, ethernet is on (does not blink) then dsl the connection lights up and starts (flashing) - that is, it turns out that something gives a disconnect and then again goes on a new connection ...
During the loss of the Internet, the ping shows the following - the router pings normally, and Internet sites 4 losses out of 4 packets.
Who faced pliz help solve the problem)

Answer 1

Judging by the description, the DSL link is lost. If spring started two weeks ago and the snow is melting, then the telephone cable is probably wet. Experiment with DSL modes on the modem, if it does not help, file a complaint with the telephone operators. They are unlikely to replace the cable, but they may find another working pair in it.
PS well, locally check everything that can affect the quality of the link - twists, sockets, everything that can interfere with the telephone cable, for example, nearby GSM equipment. It may well be that you put your cell phone next to the modem.

Answer 2

The fastest interference on the line. You need to go to the DSL settings of the zyxel 600 series modem, and look at the SNR Margin coefficients - Signal Noise Rate, Line Attenuation.
What is it - you can look for example here
Then contact the provider regarding improving the quality of the line.

Answer 3

Your modem is dead

Answer 4

not necessarily a modem, if the Internet is from Rostelecom and you live in the Leningrad region, call the provider and take out their brains