Forgot to post all of November so this will be a big update:
Had issues with laptop, which was intended to be used for pentesting the Ubuntu router (in fact Windows crashed and burned so I had to reformat my laptop's hard drive and ended up installing Linux instead). In the meantime I instead created a virtual Kali Linux machine on the same host as the router but on a separate virtual network to act as pentester.
Had trouble getting virtual Kali machine to communicate with Ubuntu router. VirtualBox manual not really clear on how to get two virtual machines on separate networks to communicate, and Google was not very helpful. Resolved by just setting up separate adapters on each machine that could ping each other.
Pentesting went about as well as I'd expect. Not very good at hacking myself so I had to use articles/videos to help with things to test and applications to use. Also tested the ping speeds from servers to each other within the network as well as out to Internet like google.com and the like.
Pentesting is mostly done although I'm still researching other hacking techniques to really get a good feel for the effectiveness of an Ubuntu router. Also documenting finds to create a PowerPoint to present my findings.