I have a Peplink 310 and I was wondering if there was any way to access its interface through DynDNS? Basically what I am trying to do is to be able to manipulate and access the routers settings outside the local network.
Yes. That is exactly what I am doing with my Peplink Balance at home. It is as simple as entering your DynDNS hostname along with your account username and password on the desired WAN interface. Peplink will then update this WAN IP to DynDNS when needed to keep it pointing to the right direction.
And be sure to change WAN Admin Access from LAN Only to LAN/WAN under System > Admin Security to allow WAN admin access 
Okay so I setup dynamic dns and its working through the peplink router, but I still can’t access the peplink interface. I had setup dynamic dns before but through one of the wan port routers, a net gear to be precise, and not the peplink itself and I must have forgotten to assign a port to a certain device (dvr). So when I access my host name it takes me to the dvr by default. The problem is I am not currently at my house and I can only access my network remotely to make adjustments. Is there any way to se a specific port for the peplink so I can access it like www.hostname.com:XXXX?
Edit: nevermind I must have missed the last line you wrote while reading your post. Going into system>admin security was the step I missed. Thank you so much for all your help!
Glad to know it is working well for ya Enjoy your Peplink.