I'm staying at Nanyang Hotel in Wan Chai, Hong Kong. Which port is closer to the mainland?

You can take the cross-harbour tunnel bus under the hotel, and you can take the buses 10 111,1 15. Just take one stop and get off after the tunnel. Walk 2-3 minutes to Hung Hom Station and buy a one-way ticket (it is more convenient if you have an Octopus card, and you can take both buses and trains). You can take the train directly to Luohu Port or Futian Port, whichever you choose. The two ports are on the same line, so it should be the nearest port.

I hope I can help you.