timer speeds on different computers

im making an online 2 player game and used timers

i have a laptop and a desktop and i ran the game and connected them two over the network

the timer intervals are the same obviously because its the same exe file that im running

in my game, u can move around and the timer makes u move around

i line up in the game on the left side of the screen and race to the right side of the screen and the result is that my laptop hits the other side 4 seconds before my desktop does, even though my desktop should be faster.

is there any way to get the timers to run at the same speed? this will greatly affect the online gameplay if i cant fix this. the bullets that you can shoot will be traveling at different speeds causing a great advantage for the comp that is running the timer faster

It's really unreliable to use a timer for exact measurements.
I'm not sure how you could make them the same, unless you manually tweak the intervals on each different computer until they are all the same, but that is probably not viable