I'm having the exact issue. I'm paying for Blast internet and this just started in the last month or so. I checked resmon and nothing was clogging up the bandwidth or using anything else, really. I tried to reach out to a technician but every time i do it replaced my sign-in name with "true" and says I can't chat unless i have a valid account number.
I'm honestly so sick of their service and how difficult they make it to get support on issues that are clearly their fault. Maybe I'll just switch to verizon if this constant issue doesn't stop before I move at the end of the month.
~Start here: troubleshooting guide. If you still need help, please post your equipment details (make/model of your modem/gateway/router) and a screenshot of your signal levels and your error/event log. Thank you!