It's about router or modem or internet connection problem or else
You will have to refresh 20+ times, re-add IP 10+ times, re-open SAMP.exe windows 5+ times
Restart 2-3 times, re-install samp.exe 2 times, repeat
If not work, move all files in "Rock Stars Games\GTA San Andreas" folder to new one (such as "Rock Stars Ganes\GTA SA2")
Check if anything wrong with modem, router, internet signal, or else, contact ur internet company
If nothing work, re-install GTA SA, SAMP, and delete all GTA SA contains files and folders
It's should fix, if not: Format