Windows 10: Unable to access my router admin page

Hi there everyone,I have an ASUS RT-AX86U router for one and half year now. I've been using it always with the same setup - laptop connected via ethernet cable - and I was always able to access its admin page via browser.Yesterday, I connected for the first time an HDD to the router, so I can use it as shared drive. So far so good, my TV can see it on the network, my laptop and other family members as well.While on my laptop, I opened the file explorer and went to Network and clicked on the new device. Some Windows info came up that I accidentally clicked on it. And I think this was THE thing

:)

 

Unable to access the Admin page of my modem router since latest Windows 10 update

Since I updated the latest Win 10 update, I am unable to access my modem router's admin page. I previously never had any problems logging to the admin page. I took the extra step of uninstalling my antivirus/firewall program and logging in to no effect.
I can access the internet and have no issues in viewing any website. The only time I have been able to access the modem router admin page since the last Windows 10 update is when I start windows in Safe Mode with networking. Refer message below:

Your Internet access is blocked
Firewall or antivirus software may have blocked the connection.

Try:

• Checking the connection
• Checking firewall and antivirus configurations
• Running Windows Network Diagnostics

ERR_NETWORK_ACCESS_DENIED

Check your Internet connection
Check any cables and reboot any routers, modems or other network devices you may be using.

Allow Chrome to access the network in your firewall or antivirus settings.

If it is already listed as a program allowed to access the network, try removing it from the list and adding it again.

 

Can't access router admin page on private network

I have noticed that I am unable to access my router's admin/log in page if my network is set to private. I have checked to make the sure that the browsers are on the list of apps to be allowed through the firewall. I have disabled Windows Defender. I have
checked 3 different browsers. The only thing that works is switching my network to Public and it connects right away. This is the error I get on private.

Hmmm… your Internet access is blocked

Firewall, antivirus software, or Windows Information Protection policy may have blocked the connection.

Try:

• Checking the connection
• Checking firewall and antivirus configurations
• Running Windows Network Diagnostics
• Contacting your network administrator

ERR_NETWORK_ACCESS_DENIED

 

Unable to access router's configuration page (192.168.1.1)

If it is one of those lovely TP-Link bugs, then all bets are off. However, try some basic troubleshooting first:

• Disconnect the WAN-side cable (phone line or ethernet, assuming it is either of these).
  
• Also applies to LAN-side access: Make sure you access it with ethernet cable and isolate the router to just the one ethernet cable and client PC that you're trying to access the config page with.
  
• Do all this before booting the router to make sure the boot is 'clean'.
  Do you see the same issue?
  

If not, it suggests that something is interfering when other connections (WAN, LAN, WiFi) are plugged-in/active.

This may be at worst, a specific attacker, or otherwise anything of: some buggy process on any connected device, or some network connection type (overloading, bug, etc).
As suggested, the router running out of RAM (and a bug in handling this condition) is a common problem, especially under heavy load.

Also, check that there isn't some sort of firewall setting on the router (or even your PC) blocking your client IP from accessing the web interface. Some routers support this.

I would strongly suggest to always disable uPnP as mligor has suggested.
It is way too much of a security risk and if you need to open ports instead of uPnP's automated method, do it manually and learn what this entails.
Also, disable remote administration and set a strong admin password.