(In reply to bert from comment #13) > Even when using a proxy, a connection test can be performed. For instance Windows attempts to download https://ipv6.msftconnecttest.com/connecttest.txt and uses this to determine whether it has IPv6 connectivity or not. This works just fine through a proxy. It can detect if the current network has IPv6 connectivity and Firefox is already doing a similar check (access to `http://detectportal.firefox.com/success.txt?ipv6`). But it cannot detect if the origin server provides an IPv6 connection if proxy or socks is configured. We also have to check the latter.
Bug 1912610 Comment 14 Edit History
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(In reply to bert from comment #13) > Depending on environment, you might need an AAAA lookup to reach the proxy. If you blindly disable AAAA lookups because a proxy is configured, this would break. I mean we should disable the check that we are going to add in the error page. It does not affect any existing network connection because currently we do not send the AAAA query at all. > Even when using a proxy, a connection test can be performed. For instance Windows attempts to download https://ipv6.msftconnecttest.com/connecttest.txt and uses this to determine whether it has IPv6 connectivity or not. This works just fine through a proxy. It can detect if the current network has IPv6 connectivity and Firefox is already doing a similar check (access to `http://detectportal.firefox.com/success.txt?ipv6`). But it cannot detect if the origin server provides an IPv6 connection if proxy or socks is configured. We also have to check the latter.
(In reply to bert from comment #13) > Depending on environment, you might need an AAAA lookup to reach the proxy. If you blindly disable AAAA lookups because a proxy is configured, this would break. I mean we should disable the check that we are going to add in the error page. It does not affect any existing network connection because the query will be sent only if the connection failed and currently we do not send the AAAA query at all. > Even when using a proxy, a connection test can be performed. For instance Windows attempts to download https://ipv6.msftconnecttest.com/connecttest.txt and uses this to determine whether it has IPv6 connectivity or not. This works just fine through a proxy. It can detect if the current network has IPv6 connectivity and Firefox is already doing a similar check (access to `http://detectportal.firefox.com/success.txt?ipv6`). But it cannot detect if the origin server provides an IPv6 connection if proxy or socks is configured. We also have to check the latter.