As someone else mentioned, you'd be getting it for work, so it's tax deductible.
Obviously we don't know your situation, but if I had system problems that were continually causing 2-3% downtime, I'd be working all hours of the day (and night) to fix it so that I don't have to stretch out the fix to an even longer period of time. I realize that's probably not all you're doing at work, but this sounds a bit like putting off stuff that's not fun. Plow in, head down, get it done so that issue (or those issues) don't cause you any more late nights.
That said, you also sound a bit unsure of the future - not much money left, trying to become profitable, etc. Are you looking for another position? If so, I would expect most other orgs would expect 'internet at home' from a CTO - especially one with an equity stake (however small).