Can't connect to RT-AC88U

Two weeks ago, DD-WRT was installed on this router and the Web GUI was accessible. The router could be rebooted and connected to.

After powering on the router today, I am unable to connect to the Web GUI at http://192.168.0.1. or https://192.168.0.1.

The only Ethernet client is able to pull a DHCP address.

Any ideas ?