Woke up to weird sound. Fragile, DDOS attack and remote access all in my AX6000 router log.

As for any strange noises, the router would not make any beyond probably slight noises from inductors and other coils when sending data to multiple WiFi clients.

Alexa enabled devices can sometimes make noises if they encounter anything similar to the wake word, or even random combinations of noise. Since Alexa doesn't constantly transmit audio to a remote server for processing when it comes to basic commands, instead it uses a special tyle of frequency pattern recognition where it will respond to its name, but also various other sounds, including super high pitched noise. The reason is that it is not truly listening to the words, instead it is analyzing an FFT. It is also why ads can say the wake words without triggering it, by simply processing the audio with a notch filter somewhere in the 3000-6000Hz range depending on the voice saying the wake word. It distrupts the pattern enough to make it not recognize it as a wake word. Though strange things can activate the wake word. For example, if I place my alexa device too close to the HVAC system and the air conditioning comes on while during the startup sequence the hot water heater also comes on which triggers the draft inducer fan to come on, it will make the echo device think the wake word was said, even though it sounds 100% nothing like the wake word.