MacBook internet works, then slows then stops…

Well, I am a Windows user trying to learn her first MAC (M2 Air), but work in IT supporting Windows devices so my first thoughts are coming from that side of the house...

First, confirm that you still have an IP address by looking in SYSTEM SETTINGS, either WIRELESS or NETWORK USB LAN if using a ethernet dongle. If wireless, do you still see your wireless and all your neighbors wireless networks listed? If so, I would open a TERMINAL(found in FINDER/APPLICATIONS/UTILITIES) and ping the gateway- your router's IP as listed in the Wi-Fi or USB LAN Details as ROUTER. If not familiar with ping, just type "ping (use the address that shows as ROUTER)". Hit CTRL+z to stop it after a few reps. Does it get replies or timeouts? If you get replies, try pinging google.com. Replies, timeouts or "ping: cannot resolve google.com".

Yea I know the whole argument MAC vs. antivirus software; some say it's a waste of processor 'heck it's a mac' whatever. As a Windows person, if Malwarebytes (which I do use) finds something, that means there are 4 more that it didn't find, I still don't think its forte is antivirus, it's more malware I don't care what they call themselves. You might want to install a trial of something else like Mcafee or Bitdefender or similar and run the full scan just to see what a more fully featured real antivirus product could spot. And yes I do use an AV product + Malwarebytes on my Windows boxes. On the MAC I just installed F-Secure which is a freebe from my ISP, while I scope out if anything else is really any better and worth paying for.

Something about that network vs. that MAC. When it fails, did you open SYSTEM SETTINGS/WI-FI and click DETAILS to see if you still have an IP address? Try 'Forget This Network' and disconnect from it. I would even turn the wireless OFF, wait a few moments, then turn it back ON (in Windows it's all about power cycling, disabling, enabling LOL but it can't hurt here). Now reconnect, supplying the wireless key again and test it again. I don't know if you have the MAC firewall on, but you could also try turning that off (yea longshot) as a test. Could even be something about the wireless access point (I don't know what you are using on the network) but that's beyond the scope of this place... You may have to end up power cycling your router/wireless access point(s) if the issue is there (another long shot).

Well, if you have access to other computers, maybe downloading Bitdefender or Avast on one of them, and transferring it over to the problem MAC with a usb stick if you can't download it with the MAC? They are available at their respective websites and are legit. And I am sure there are others, those two popped up with a web search and I know they are legit companies/products if from their official websites. They seem to get good reviews.

Interesting about it working for a few moments after PING.