yeah, yours sounds like it was more of an internet problem, so local server was definitely the right choice for you. ScottM sounds like he has a less than ideal wifi setup, so I'd recommend starting there with making changes.
Scott, can you take the oak upstairs to update it? or even moving to other locations in the basement might help you get a stronger signal?
Or could you run the firmware update at a friend's house?
Or Some people found updating via mobile phone acting as a hotspot for their mobile data worked for them.
Basically there are plenty of tricks you can try yet, don't give up, I'm sure you get there. And once the firmware is loaded, typically you'll have no more wifi issues... so just get it in by whatever means works best.
Good luck.