Arris TG1672 Modem
I want to know what wireless extender would work best with this modem?
The Arris TG1672 is a 2.4 GHz device so any single 2.4 GHz band extender should be compatible.
I don't recommend extenders due to the fact that by design, they essentially cut data throughput in half in the process of attempting to extend the range.
I personally believe you're better off running a higher quality router from the Arris TG1672 Modem.