Ac1750 Speed

First let me start off by saying I am not really knowledgable with router knowledge. My home interenet speed is 200/200 and i was hitting around 170mbps using my AC1750 router. Then about 4 months ago,this speed went down to around 60mbps. I then switched to my fios router and that is hitting close to 200mbps. The problem is that the fios router sucks when it comes to signal and i want to use my AC1750. Is there something I am doing wrong? Is my router old and maybe just need to buy a new one? Thank you all in advance for you help.