(Update) Bought a Router/Modem on bad tech suggestion. Should I use new router/modem and replace a Netgear C3700?

I bought a TP-Link AC1750 (Archer A7) and a Netgear CM 600 from bad advice from COX tech support (thread here).  Chat support suggested my C3700 was at its end of life and needed to be replaced. The problem was my wiring.  After getting techs here to address my bad wiring, my signal improved and my WIFI (and signal) is now rock solid.

Question:

Is there a reason I should keep the newTP-Link AC1750 (Archer A7) and a Netgear CM 600 to replace my old Netgear C3700?  Is the 8x4 a concern? 

Another concern I have regarding replacing my old equipment is, when I check my logs, I see

[DoS attack: Teardrop or derivative] .....

[DoS attack: Ping Of Death] from ....

[DoS attack: Illegal Fragments] from ....

[DoS attack: Teardrop or derivative] from ....

Apparently, this is a common problem [1][2][3][4].

I am unclear if these are false positives or a reason to swap out this modem combo.