Can't connect using Safari as of update this week Secure connection fails

One day everything worked fine, the next can’t establish a secure connection. Same thing in Firefox but Vivaldi and Opera will establish connection. I sent detailed info to the developers but have had no response.

Additional information:

Messages appearing in Console after attempting to load OGS.

SAFARI
Set marker. Load URL h ttps://online-go.com

2/17/17 12:17:51.076 AM com.apple.launchd[1]: (com.avast.update) Throttling respawn: Will start in 7805 seconds
2/17/17 12:20:39.229 AM com.avast.proxy[269]: SecTrustEvaluate(): online-go.com: 7
2/17/17 12:20:39.229 AM com.apple.WebKit.Networking[544]: CFNetwork SSLHandshake failed (-9806)
2/17/17 12:20:39.231 AM com.avast.proxy[269]: SSL_accept(): Broken pipe
2/17/17 12:20:39.247 AM com.avast.proxy[269]: SSL_accept(): inappropriate fallback
2/17/17 12:20:39.247 AM com.apple.WebKit.Networking[544]: CFNetwork SSLHandshake failed (-9802)
2/17/17 12:20:39.270 AM com.avast.proxy[269]: SSL_accept(): wrong version number
2/17/17 12:20:39.270 AM com.apple.WebKit.Networking[544]: CFNetwork SSLHandshake failed (-9824)
2/17/17 12:20:39.271 AM com.apple.WebKit.Networking[544]: NSURLConnection/CFURLConnection HTTP load failed (kCFStreamErrorDomainSSL, -9824)

FIREFOX
Set marker. Load URL h ttps://online-go.com

2/17/17 12:29:35.751 AM com.avast.proxy[269]: SecTrustEvaluate(): online-go.com: 7
2/17/17 12:29:35.753 AM com.avast.proxy[269]: SSL_accept(): Broken pipe

Feb 17 00:29:26 MacBook-Pro.local Console[3666]: Marker - Feb 17, 2017, 12:29:26 AM
Feb 17 00:29:35 MacBook-Pro.local com.avast.proxy[269]: SecTrustEvaluate(): online-go.com: 7
Feb 17 00:29:35 MacBook-Pro.local com.avast.proxy[269]: SSL_accept(): Broken pipe

Firefox notification page:

Secure Connection Failed
The connection to online-go.com was interrupted while the page was loading.
The page you are trying to view cannot be shown because the authenticity of the received data could not be verified.
Please contact the website owners to inform them of this problem.

VIVALDI
Set marker. Load URL h ttps://online-go.com

2/17/17 12:37:22.000 AM kernel[0]: Vivaldi Helper (map: 0xffffff8053f4df00) triggered DYLD shared region unnest for map: 0xffffff8053f4df00, region 0x7fff8d800000->0x7fff8da00000. While not abnormal for debuggers, this increases system memory footprint until the target exits.
2/17/17 12:37:51.030 AM com.apple.launchd[1]: (com.avast.secureline.update) Throttling respawn: Will start in 6605 seconds
2/17/17 12:37:51.030 AM com.apple.launchd[1]: (com.avast.update) Throttling respawn: Will start in 6605 seconds

As of 17Feb2017 still get same result. Using Keychain Certificate Assistant, Evaluate Code Signing gives Evaluation Status: Invalid Extended Key Usage.

Get this in Console when I tried to load the site.
2/17/17 11:24:11.505 PM Console[10769]: Marker - Feb 17, 2017, 11:24:11 PM
2/17/17 11:24:18.071 PM com.avast.proxy[269]: SecTrustEvaluate(): online-go.com: 7
2/17/17 11:24:18.072 PM com.apple.WebKit.Networking[544]: CFNetwork SSLHandshake failed (-9806)
2/17/17 11:24:18.073 PM com.avast.proxy[269]: SSL_accept(): Broken pipe
2/17/17 11:24:18.089 PM com.avast.proxy[269]: SSL_accept(): inappropriate fallback
2/17/17 11:24:18.090 PM com.apple.WebKit.Networking[544]: CFNetwork SSLHandshake failed (-9802)
2/17/17 11:24:18.110 PM com.avast.proxy[269]: SSL_accept(): wrong version number
2/17/17 11:24:18.111 PM com.apple.WebKit.Networking[544]: CFNetwork SSLHandshake failed (-9824)
2/17/17 11:24:18.112 PM com.apple.WebKit.Networking[544]: NSURLConnection/CFURLConnection HTTP load failed (kCFStreamErrorDomainSSL, -9824)
2/17/17 11:24:18.119 PM com.avast.proxy[269]: SecTrustEvaluate(): online-go.com: 7
2/17/17 11:24:18.121 PM com.avast.proxy[269]: SSL_accept(): EOF