AC1900 R7000V2 Telenet

I purchased this modem/router combo last year and I was able to get into the modem and add a static ip+mac with telnet. The modem has been reset and I havenot been able to get into it as of now. I'm trying to add a static IP with a my macaddress for WOL reasons. I have WOL working without any issues. On Lan and on internet. The problem I'm having is the arp table will drop my IP and Mac address after 10-15 minutes. Any suggestions on this one? The main reason for doing this is to be able to wake up my pc from work and out of the office lan