Sometimes, Avast will block some URLs.
Then, lets get some information about the Avast URL: Blacklist.
How to Manage URL: Blacklist
How to Manage URL: Blacklist on your Windows 10?

Here is a guide.
Avast provides a whitelist.
To except URLs from Avast protection, you gotta do the following steps.

Step 1:Open Avast on your system and go to the Avast dashboard.
Step 2:Then clickMenuand click theSettingstab.
Click theExceptionstab under theGeneraltab
Step 3:Under this tab, clickADD EXCEPTIONand a new window will pop up.
Then you could bang out the URL that you want to add in it.
Step 4:ClickADD EXCEPTIONto save the URL.
Then you should go back to your internet tool and attempt to get into the URL.
Way 2: Temporarily Turn Off Avast Protection
Step 1:Go to Windows 10 taskbar.
Right-nudge the Avast antivirus icon and choose theAvast shield controloption from the menu.
Step 2:Choose one option from the following options to disable Avast protection temporarily.
I hope that this post can be helpful to you.