Updated FAQ (markdown)

FAQ.md

@@ -112,6 +112,17 @@ Usually the logs are collected during a long period of time span. Let's say each
 gRPC can be derived from the `-port` number and adding 10000 ontop of it. 
 `-port=8080` => gRPC Port: `18080`
 
+## Support ipv6?
+Yes. A common error is when binding a link-scoped ipv6 address without a proper scope. This will cause `connect: invalid argument`.
+
+e.g.
+```
+# invalid
+-ip="[fe80::4c3:3cff:fe4f:7e0b]"
+# valid
+-ip="[fe80::4c3:3cff:fe4f:7e0b%eth0]"
+```
+
 ## Mount Filer
 ### weed mount error after restarting