a question about port scanning

have read many threads on this subject,however the answers i seek are not there. ok so ,nothing to worry about maybe, but curios. here goes. Some firewalls give notices when this occurs. Malwarebytes was popping these 50 times a day.(fairly constant). Should firewall stop these,instead of MBM. I have windows firewall.????
Dont have money to invest in a router.

 

Could be something more prevalent with the cable internet ? Not getting notices as of yesterday because MBM trial for extras ended. Just seems funny where I read that people that get the pop up notices,usually come from a firewall not from MBM. So i understand this goes on all the time. And as long as firewall is on it will be ok.
? With cable internet i get these even when i am not using internet. Does this still happen with dial-up or wireless ?
Kind of seems like I dont want to turn firewall off ever for any reason whatsoever,if plugged in. ?