Most of Wales' universities say they are delaying a return to in-person teaching because of the new coronavirus variant.
The Welsh Government has resisted calls for a Wales-wide timetable for students returning.
But on Friday it said students should stay at home if they can.
The National Union of Students (NUS) said students were confused and anxious and called on the Welsh Government to give a "crystal clear" message.
Students studying in England and Scotland have been told not to return until late February at the earliest.
The Welsh Government said institutions would look at "individual circumstances within national guidance" as part of a phased return from 11 January.
What have the universities said?
Most of Wales' eight universities have advised students not to come onto campus as Wales' lockdown continues due to high coronavirus rates.
Wrexham's Glyndwr University, which has campuses in Wrexham, Northop in Flintshire and St Asaph in Denbighshire, remains open for some "essential on-campus teaching" where students will follow "all Covid-19 guidance" and have a test.
Wrexham currently has the highest Covid infection rate in the country followed by Flintshire and Bridgend.
Cardiff, Swansea and the University of Wales Trinity St David - which has campuses in Carmarthen, Lampeter and Swansea - said face to face teaching for the vast majority of students would not resume until at least mid-February.
Aberystwyth University has urged students not to return for the time being unless "absolutely necessary".
Bangor University said attendance for most students would not be mandatory until 8 February at the earliest while teaching at Cardiff Metropolitan University will be online only until at least 1 February.
University of South Wales, which has campuses in Cardiff, Newport and Pontypridd, said it would continue to deliver teaching remotely until at least the week commencing 22 February.
'Confused and anxious'
"Universities were originally told to plan for all students to be back in in-person teaching over a four-week period starting January 11, with students on practical courses returning first," said NUS Wales President Becky Ricketts.
"Students have become confused and anxious about if and when they should be returning to campus.
"The Welsh Government needs to be crystal clear to students that the message is to study from home if you can.
"Universities also need to communicate their updated plans with their students as soon as possible, so they can make informed decisions."
The head of one higher education think tank said the absence of a clear message from ministers made it hard for students to work out what is going on.
Nick Hillman, director of the Higher Education Policy Institute, said: "I think the problem is students don't really know where they are.
"There isn't a clear message coming out of the government in Cardiff.
"There is instead episodic messages coming out from individual institutions on different time scales and it's very hard for students, some of whom are pretty young - a lot of them only left school less than a year ago - to really work out what's going on and at what point, they should return to their student accommodation and expect face to face teaching to happen".
He said the issue was that it was tied up with "big financial issues" and calls from students for refunds for tuition fee and accommodation costs.
"Many people think the Westminster Government should start thinking about tuition fee refunds for people, which would have a knock on consequence for funding and Wales as well."
The Welsh Government said it had asked universities to update plans in light of the new coronavirus variant.
"Our message to students, staff and universities in general is the same as the rest of the population: Stay home, work or study from home if you can," said a government statement.
"Only attend your place of work or study if you can't work from home".