Know that ANY bit of adverts, as passive community influx, will be minimal. You already mentioned that you've loaded your server on multiple sites, which is great! But your adverts can extend PAST standard minecraft websites.
Networking over multiple platforms have the capability to grab the eyes of people who aren't necessarily looking for a server to play on, but you MIGHT peek their interest depending on how you post your adverts.
With that said, look into creating a server accounts on Instagram, Facebook, YouTube, TikTok... ect.
Focus on the type of community you are looking for as well.
Builders, Explorers, PVP, Games, Puzzles, Parkour, Roll players, Survivalists, Redstoners...
Post material that would interest those specific people.
PMC bumps - Regularly bump your PMC post at times you are usually on your server. This will bring people in during times that will give you an opportunity to give them a tour and answer questions.
Work with your current community. Encourage your people to vote for your server, like & comment on your posts, write individual reviews, post Lets Plays and builds involving your server.
Hope this helps
