Gunganator

Don't worry about the internal test, it's not always going to be accurate. You said your ISP hub died so what's the setup now specifically? 
I've given you Early Access to try that firmware: https://forum.netduma.com/forum/144-netduma-r2-early-access/

Ah okay, I think it'll be due to using PPPoE and that'll be the max you can achieve while having the R2 handle it.

I've not encountered anyone mentioning the R3 overheating thus far and given we're in the height of summer I'd take that as a good sign!