Netgear WNDR3800 suddenly stopped connecting to the internet

Using openwrt Chaos calmer/Netgear wndr3800 for maybe 2 years. Upgraded to 18.06 working fine for appr. 5 months with 18.06. Suddenly router stops working. Turns out nothing is wrong. Loose connection at power. Works fine once – able to access internet. Router powered off / on... now can’t access internet. Wireless works fine. Upgraded to 19.07… still can’t access internet, wireless fine.

How do i get it working again?
What logs / files could help you help me?

thank you,