I have a ubiquiti router that allows for dual input (other brands may allow for this as well), this way when signal/connectivity is lost it leverages the backup provider which could be a different carrier ... might be a nice setup for you.
Redundant Internet
My power went out last night for about 5 hours. Despite my network hardware being on a UPS, the Internet service went out anyway. Seems they use the same power feed my house does. When the power came back on late last night the Internet did not.
This used to be routine, then they fixed it, now we are back to unreliable.
As a result I’m investing in an inexpensive edge router and getting TMobile home internet as a fallback. The long term reviews for Tmobile home Internet were mixed. At first users loved it, then after a couple of months the performance seems to have deteriorated significantly. Hopefully it is now better an with a little luck I won’t have both go out at once.