Mystical behavior of Zyxel P660RT2 ADSL modem?

Question

Computer networks

I get Internet via ADSL modem Zyxel P660RT2 from the Ukrainian provider Ukrtelecom, tariff 10Mb. The connection is configured via PPPoE. The modem is connected in router mode.
Until recently, everything was fine, the speed was a little short of the tariff 10Mb, but it was close to it. About a month and a half ago, brakes became noticeable (slowly opening pages, slow youtube).
Speed ​​measurements show a speed of about 1Mb (download), files via http and ftp are downloaded at a speed of about 100 kilobytes per second (by browser and downloaders).
Now, the fun part: torrents with a lot of seeds download at full speed (about 900 kilobytes per second).
I also have an old Zyxel P660HW modem with a broken twisted pair router, but working ADSL and WiFi parts. Everything works as it should on it: the measurements show a speed of about 8MB, the files are downloaded at a speed of under 900KB.
Who will have any ideas? What could be the problem with the first modem (P660RT2)?
I reset the settings on the modem to the factory settings - it did not help.
Usually the modem is connected to the router, for verification I connected it directly to the computer - the same problems. Moreover, I connected not the main computer, but a netbook, which I rarely use and on it, apart from Windows XP, little is installed (this excludes the possibility that some kind of virus lives on the computer, taking away the entire Internet).
I have absolutely no idea what else can be done. Please help! Where else can you dig? What to watch?

Answer 1

Firmware updated?

Answer 2

If a PSU is suitable from an old modem, try it on the current one.

Answer 3

I would first update the firmware, if it does not help, then reset the settings and set it up again.
By the way, I remembered that I had something similar - it was treated by rebooting the modem until an ip was assigned from another pool (94.xxx or 178.xxx). Then everything went by itself.

Answer 4

Have you tried changing the splitter or turning it on without it?

Answer 5

Does the modem get very hot during operation?