The latest firmware listed is from 2014, and I see in the router logs that it checks every day for an update (and has been doing so for a long long time) saying the check failed, and I traced that because the url info shows no such page exists on the actiontec site. The FAQ's from Actiontec say the ISP (verizon) would provide any firmware updates, but as I started out saying, THERE HAVEN'T BEEN ANY SINCE 2014. IS THAT THE LATEST for this router??????
My firmware is also 40.21.18 as well. (My unit seems like its running fine, but at the moment its just configured to be a MoCA bridge, not my actual firewall)
Given that the G1100 is the new standard router now that Verizon gives, I doubt there will be any updates to the older MI424WR models. In fact here in my area Verizon has been swapping out the MI424WR models for their G1100, seems their trying to replace them all together.