Indian Railways — new delhi railway station waiting room issue

I had connecting train from delhi to dehradun, departure time 15 :20 (Myself coming from hyderbad) but i reached on 12:00 at new delhi station and its 3hr 20 min. Since my hyderabad to delhi train reached on time. But i was told (Written on gate also) i cannot enter in waiting room since its more than 2hrs.
My request is, it should be change atleast 5hr, atleast for people come for connecting train because in india generally trains are late so we travel intentionally with some time gap.