外语老师 means the teacher who teaches students foreign languages，usually the teacher is not foreign people.外语老师 is the abbreviation of 教外语的老师，but when we want to say the student who learn foreign language，we say 学外语的学生，if youmust say its abbreviation， 学生 is OK，we don't 外语学生 cause it has more than one meaning，I don't know if you know【歧义】，on one hand ，外语学生means 学外语的学生，on the other hand it can be understood as 说外语的学生，and so on.Because it is a strange phrase，we can explain it in many ways.it is not 【约定俗成】.after all ，if you want to say it ，you can say it，and tell other people what exactly you mean.Chinese is kind of very creative language.people create words every day.you know your question is very nice：）I hope my answer can help you little

I agree with your teacher. Generally, as a Chinese student, his/her 外语老师 mostly is Chinese too and teaches him/her English; while the Foreign teacher of this Chinese student, we often call this teacher as 外教. To a teacher, when we call him/her, we often add the subject he/ she teaches before 老师. 外语学生 sounds so werid, you mean 外国学生( the students are from other countries in China.) or 外语专业的学生(the students whose major is English or other languages, except Chinese, in China. ) I guess, you are a 外国学生, and I am a 外语专业的学生.

it is depends on what you want to express. 外語學生 also correct in its sence of the study foreigner language's student. 學外語的學生 also corrects in it sence of the student who study foreigner language. don't worry there is no mistake in both.

Thanks, great explanation!

Haha,well,you can call students from foreign language department as 外语系学生.Students learning a foreign language are called 学外语的学生. Good luck! PS:i think it's just a habit of saying 外语老师,which means 教外语的老师. 外语学生 sounds odd to me.