I was rolling back from OpenWrt firmware to the old one. It seems ok but when I tried to enter the login panel it was not working. I reset it.
After resetting, the power and LAN LEDs came on, but I could still not enter. The default gateway was rolled back to 192.168.1.1, but I failed to enter there. Using Wireshark software, I discovered that I was failing to enter that IP address.
Guessing here, but it is likely that you have a snapshot installed... if so, the following applies (although you may want to use a normal stable release instead):
You have installed a snapshot image. Read the link for instructions how to install Luci, which is not installed by default in snapshots.
I also encountered this problem, and recompiling the firmware did not make it work. And I found that only the Chrome browser would report an error, but Edge was normal.