pordisto

Decode it and you are done. Pordo at rank 171 is a door. -Ist- is the profession suffix you met in the affix track: the person who does this thing for a living. Pordisto is therefore the door person, and every English translation of it (doorman, doorkeeper, porter, concierge, janitor, gatekeeper) is a different accident of English rather than a different Esperanto word.

The suffix is the lesson, not the word. You already have kuracisto from kuraci, servisto from servi, oficisto from ofico. Pordisto is the same machine applied to a noun rather than a verb, which is allowed and common: ĝardenisto, fiŝisto, maŝinisto. Once you notice that -ist- attaches to whatever the job is about, you stop learning job titles one at a time.

The near neighbours worth separating. A pordisto sits at a specific door and controls who comes through it, typically at a hotelo or a large domo. A gardisto guards a thing and may roam. A portisto, built on porti rather than pordo, carries luggage, and English porter unhelpfully covers both jobs. Esperanto keeps them one letter and one whole meaning apart, so pronounce the d clearly.