Without internet access, Steam remains functional through local storage and offline gameplay options.
Without internet access, Steam remains functional through local storage and offline gameplay options.
Interestingly, I have two systems that function smoothly in Offline Mode without needing internet, while the third one requires constant internet access to operate.
That is a horror story. I've heard Steam only works for a few weeks in Offline mode before it needs to contact Valve's servers again anyway, so unfortunately even if you find a way to get that working it may only a temporary solution. I've never really put it to the test myself, though. If you can't even log into Steam, that doesn't sound like a speed issue, that sounds like the connection is extremely unstable, probably through excessive packet loss. You may want to contact your ISP and tell them about this. Maybe it can be fixed. I don't think 1 Mbps is "too slow" for Steam to simply connect and let you play your games offline. You should complain about not getting your advertised speeds anyway.
I'm using a mobile connection, which usually means slower speeds and possible packet loss. A ping of about 2000ms is typical, and I expect some data drops along the way. It might be best to move my device to a more reliable network for smoother performance.