I couldnt access coinbase and also 8ch today. The following helped
Airplane mode on then off Navigate to Settings, then slide Airplane Mode to On, wait a few seconds, then slide it back to Off. It seems that discontinuing and restarting the EDGE and WiFi components in the iPhone can restore connectivity.
Reset network settings Tap Settings, tap General, tap Reset, tap Reset Network Settings. This will cause your iPhone to restart, and will delete any stored Wi-Fi passwords as well as DNS settings and more. It can restore your ability to join a stubborn wireless network, let you access stalled Web pages, or eliminate issues with EDGE data access that can occur for various reasons.
Use IP address of Web site If a DNS problem is indeed at play, you can sometimes get around it by directly entering the IP address of a server, rather than its domain name. Navigate to a WHOIS tool, like this one, and enter the domain name, scroll down and find the IP address, then enter it in Safari. Tedious, but sometimes effective.
Reboot your iPhone Hold down the home and sleep buttons simultaneously until you see the white Apple logo, indicating that your iPhone has restarted.