Unable to login to router

Hello John, 
Thank you for contacting AVG Community Support.
I am sorry to know you are unable to access router. I'll certainly check and help you out. Microsoft Windows Defender disables automatically to allow AVG AntiVirus to install correctly.
Each time you connect to a new network, Enhanced Firewall automatically recognizes whether the network is private or public, and applies the relevant settings. 
Could you please provide me with more details about the situation, and I will do my best to help you resolve it efficiently. 
May I know if you selected the network as private or public in firewall?
Did you try after disabling Enhanced Firewall (https://support.avg.com/SupportArticleView?l=en&urlName=Use-AVG-Antivirus-Enhanced-Firewall&supportType=home)? 
Does a specific error message appear when you encounter this issue?
If so, please help us with the screenshot of the error you got. You can post the screenshot here in your topic. Click on Answer & then click on the Image [mountain symbol] & follow the instructions. If needed, please find a quick guide on how to take a screenshot here (https://support.avg.com/SupportArticleView?l=en&urlName=avg-create-screenshot&q=screenmshot&supportType=home). 
Awaiting your response.

AVG has blocked access to my router by overriding windows defender.  Can you advise please ?

Hello John, 
Thank you for contacting AVG Community Support.
I am sorry to know you are unable to access router. I'll certainly check and help you out. Microsoft Windows Defender disables automatically to allow AVG AntiVirus to install correctly.
Each time you connect to a new network, Enhanced Firewall automatically recognizes whether the network is private or public, and applies the relevant settings. 
Could you please provide me with more details about the situation, and I will do my best to help you resolve it efficiently. 
May I know if you selected the network as private or public in firewall?
Did you try after disabling Enhanced Firewall (https://support.avg.com/SupportArticleView?l=en&urlName=Use-AVG-Antivirus-Enhanced-Firewall&supportType=home)? 
Does a specific error message appear when you encounter this issue?
If so, please help us with the screenshot of the error you got. You can post the screenshot here in your topic. Click on Answer & then click on the Image [mountain symbol] & follow the instructions. If needed, please find a quick guide on how to take a screenshot here (https://support.avg.com/SupportArticleView?l=en&urlName=avg-create-screenshot&q=screenmshot&supportType=home). 
Awaiting your response.