Network connection timeouts on MacBook Pro
This question has been asked previously in this site (1, 2), and in many other forums, but not answered particularly well. I have, on a couple of occasions, experienced bouts of chronic network timeouts, but they have "cured themselves" after a restart. Your problem sounds persistent, and my curiosity was piqued. So here's what I found: 

From OSX Daily is an approach that requires you delete a set of files in /Library/Preferences/SystemConfiguration/. Apparently these are files the system generates, but it sounds like you'll need to re-enter the settings, and that could be an effort if you've made a lot of WiFi connections. The procedure is basically as follows: 


Turn off Wi-Fi in System Preferences or menu bar. 
Remove aall Thunderbolt or USB devoces connected  
Create a backup folder &amp; copy the files you will delete below into it


Here's the list of files to be copied to a backup folder, and then deleted from: /Library/Preferences/SystemConfiguration/: 

- com.apple.airport.preferences.plist  
- com.apple.airport.preferences.plist-new   
- com.apple.network.identification.plist   
- NetworkInterfaces.plist  
-  preferences.plist  


There is also this article from OSX Tips that, essentially, prescribes the same approach. It's recent vintage (March, 2019), and that could be taken as some sort of affirmation that it still works? 

So, if you're in the mood to be a guinea pig, try this, and let us know if it worked!