How can I troubleshoot and resolve Jagex error 1020 on my own?

Start by clearing your browser's cache and cookies, then try a different browser or an incognito/private window. If you're using a VPN or proxy, disable it temporarily. You might also try restarting your router or modem to attempt to get a new IP address from your ISP. Ensure your browser is up-to-date and disable any suspicious extensions. If the problem persists, try accessing from a different device or network to rule out local issues.