Same here. 3.0.0.4.386_45898 broke WAN Detection on my RT-AX58U.
No reset helped. Just flashing any older firmware and everything worked again.
With the 3.0.0.4.386_45898 firmware I get a lot of
http://router.asus.com/error_page.htm?flag=3 errors.
Maybe it is something wrong with redirections, because some pages works some doesn't.
The following two request were done in a PC one after the other with the only difference of the firmware change in the router:
curl -vvv
http://security.ubuntu.com
* Rebuilt URL to:
http://security.ubuntu.com/
* Trying 91.189.91.38...
* TCP_NODELAY set
* Connected to security.ubuntu.com (91.189.91.38) port 80 (#0)
> GET / HTTP/1.1
> Host: security.ubuntu.com
> User-Agent: curl/7.55.1
> Accept: */*
>
* HTTP 1.0, assume close after body
<
HTTP/1.0 302 Moved Temporarily
<
Server: wanduck
< Date: Sat, 05 May 2018 05:10:17 GMT
< Connection: close
<
Location:http://router.asus.com:80/error_page.htm?flag=3
< Content-Type: text/html
* Closing connection 0
curl -vvv
http://security.ubuntu.com
* Rebuilt URL to:
http://security.ubuntu.com/
* Trying 91.189.91.38...
* TCP_NODELAY set
* Connected to security.ubuntu.com (91.189.91.38) port 80 (#0)
> GET / HTTP/1.1
> Host: security.ubuntu.com
> User-Agent: curl/7.55.1
> Accept: */*
>
<
HTTP/1.1 301 Moved Permanently
< Date: Mon, 11 Oct 2021 12:42:32 GMT
<
Server: Apache/2.4.29 (Ubuntu)
<
Location: http://www.ubuntu.com/usn/
< Content-Length: 319
< Content-Type: text/html; charset=iso-8859-1
<
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
<html><head>
<title>301 Moved Permanently</title>
</head><body>
<h1>Moved Permanently</h1>
<p>The document has moved <a href="
http://www.ubuntu.com/usn/">here</a>.</p>
<hr>
<address>Apache/2.4.29 (Ubuntu) Server at security.ubuntu.com Port 80</address>
</body></html>
* Connection #0 to host security.ubuntu.com left intact