Hi Furanko,
Thank you for posting and welcome to the community! The first thing we'll need to know is if you are connecting directly to a modem or with a router/wireless. Also, try power cycling your modem and router if you have one. Typically you may have to do this a couple times. Wait a minute before plugging everything back in.
I'd also like to pull up your account to run diagnostics and see if your site is working properly. If you can post a recent case number or the serial number on the back/bottom of your modem that'll be great. Looking forward to your reply.
Thanks,
Chris