Most likely your modem isn't bridged.
So you have a double NAT (network address translation). Not gong to be good if you want to port forward stuff like Apex. If your not getting the speeds your are paying for I would first contact your Internet provider and complain.
The router has more to do with speeds, sometimes the cache is full and needs to be reset more often on cheaper wifi routers.
If you got the modem from Cox, check if your being charged monthly for equipment. Buying your own will save you that cost.
I would look into getting fiber (fios or att) if you can. I'm paying for 100/100 mbps since I think that's plenty fast for what I need. It only costs me ~ $65 a month.
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