What are you trying to filter? Most things can’t be filtered.
You can filter a good amount of things, such as errors
con_filter_enable 1; con_filter_text_out "Error";
It's pretty self explanatory if you wanna filter something else out, shouldn't be too hard to work out.
The only problem with con filter is that it messes up what pops up in your console sometimes, if you're getting vortex errors then your best of restarting gmod since it's an issue out of everyone's control