Regarding the physical aspects, you should consider your physical health, and the setup of your laptop and computer. If something happens to the device you are using, do you have access to another? How about the number of devices on your home wi-fi? Do you have the right modem? What about the speed of your Internet? Contact your Internet service provider.
For your physical health, think ergonomics. How do you feel? Are you rested? Any residual aches and pains from old injuries? Did you eat something before you started? My office is upstairs, and I have gotten in the habit of setting a timer on the microwave downstairs for 30 to 60 minutes so that I take breaks. To turn the timer off, I have to stop, get up, go downstairs, etc., I may set the timer for 10 or 15 minutes depending on how I feel to make sure that I take a break. During the break, stretch, I mean really stretch- taking time to stretch each group of muscles prior to going back to the computer, laptop, or other device.