Free proxies are overused. Netflix, Hulu, and banking sites will instantly block them. Do not use free Reflect4 lists for streaming or financial tasks.
Free proxies are notoriously unstable. A server listed as "Online" today may be offline tomorrow. This is why "Top" lists change hourly.
Ensure the list supports HTTP, HTTPS, and SOCKS4/5. Reflect4 typically implies SOCKS4 compatibility.
Run a ping test, but don't rely on ICMP (many proxies block it). Instead, use curl -x proxy:port -w "%time_total\n" -o /dev/null -s https://google.com.
If you want the real top list, you need to scrape it yourself. The open-source tool ReF4-Scraper crawls Shodan and Censys for devices that reflect traffic on ports 8080, 3128, and 1080. Running this tool daily gives you a proprietary list of 500-1,000 live Reflect4 proxies.