If you've decided to study at NIT Arunachal Pradesh, then you must know that it's a remote institute functioning in its temporary campus at Yupia. 

You can reach the Naharlagun railway station in Andhra Pradesh in the following ways-

• A direct train departs from New Delhi to Arunachal Pradesh; number- 22412. It travels through Lucknow, Gorakhpur, Chapra, Muzaffarpur, New Jalpaiguri, NewBongaigaon and Rangia. It'll be convenient.
• Another option of travel will be to take any train to Guwahati and interchange with the Donyi Polo Express, number- 15617. It'll go to Naharlagun.
• The next step could be to find a taxi, which you'd easily get at Naharlagun railway station. Although it'll be a costly affair; however, if the cabbie asks for around INR 150-200 then it's a great deal.
• The better option could be to hop onto the NIT AP free buses, which take students to campus as well.
• You can also try your luck on the main road where either you can make use of ITBP's buses because it is located in close proximity to NIT.

NIT buses are the best option according to many I know, it arrives on the main road between 8:30–9:00 am. You can take a lift from the locals or better yet, if you see any ITBP personnel, go ahead and travel with them as its headquarter is nearby. I've heard that there's a weekly train from New Delhi to Naharlagun. You can take that.