I use a pep link at work, solid device. Early adopter cost was high, we got one of the first 5g standalone modems on the market and spent a few grand. We also had to get a fancy antenna but it’s a solid system.

Fortigate firewalls have a performance sla that you can setup between two wans. Allows you to track ping time, jitter and bandwidth. It’s one of the ways it test for fail over. I use it to keep my isp honest. Looking at you charter, bag of dicks they are.

Until win10 becomes eol they are still a solid choice. There are tricks to get win11 to install on older cpus but that’s totally a call you have to weigh and make.

Look into a business account with ATT, which gives the added benefit of a fixed IP.