Ah yeah, it's Chromium as default on Raspian.
I did find that if you remove Chromium, Dillo works, but that's much use for any site designed since the 90s, and I couldn't get Firefox to even install.
I was wondering if it was because I only tried a 2GB Pi, but obviously that isn't the problem.
In case you've not realised yet, don't try updating the Pi. It'll try updating the kernel, at which point the installer fails, you then won't be able to boot the Pi again, and the OS will need re-installed.
I think the first drive thing was a false flag on my part, and it's all to do with ensuring the drives aren't connected during booting.
I thought at one point I had to have a drive connected for the master/LinuxCNC to load, but the unplugging discovery was made having spent several hours trying various things.
It was only when I started fresh that I realised you could leave all the drives unplugged during loading.