TIL: Energy Efficient Ethernet (EEE) in the newest firmware (8.2x) of my FritzBox is probably garbage. When set to “automatic” (which is the only setting aside of “off”), the network is super unstable between devices on the LAN/WAN and any other device. In both the LAN and the internet.
Clear suggestion: if you have connectivity issues after the update, disable EEE in your FritzBox’s network settings.