“This technology turns every router into a potential means for surveillance,” warns Julian Todt from KASTEL. “If you regularly pass by a café that operates a WiFi network, you could be identified there without noticing it and be recognized later – for example by public authorities or companies.”

Later…

Inexpensive or older routers either don’t store history at all or keep it for a short time.

Newer models can store more information for more extended periods.

https://www.thetechwire.com/how-long-does-a-router-store-history/

Way more Waymos (Way mo’ Waymos) than expected.