Is there any free WiFi network available at the boarding port in Buenos Aires (RENAPER Buquebus) for the Buquebus boat service between Buenos Aires and Montevideo?
Buenos días Maria, tenemos WIFI sin costo en la terminal de Puerto Madero. Saludos.
Which translates to: yes there is free wifi.
In normal times (the cited TripAdvisor answer is undated), yes.
Because of the Argentinian border shutdown, however, the Buquebus service is now suspended and the Buquebus terminals closed to public access.
Source (in Spanish): Buquebus Announcement