This version mainly support IPv6 service register and support udp push for Csharp client.
What's more, add some console features to enhance users' usage. And Fix many bugs and do many refactor and enhancement to increase stability.

Details see following:

Features

-[#978] Support IPv6.
-[#3917] Add metadata filter in service detail page.
-[#4132] Service list API param groupName support '*' to get all group serviceName.
-[#4670] Support Udp push for CSharp client.

Enhancement

-[#3607][#4078][#4170] Datasource pool configuration can be configured.
-[#3832] When the nacos-server fails to start, shutdown all http clients.
-[#3907] When publishConfig, if type is absent, set default value 'text'.
-[#4066] Make serviceNameList followed string order.
-[#4090] Configuration file changes do not take effect.
-[#4286] When auth open, use resource parser cache to parse resource.
-[#4291] In stand-alone mode, the service module does not enable the Raft protocol.
-[#4355] Do not retry distro sync again if member has removed.
-[#4463] Add auth check for SQL query of config derby database.
-[#4513] Check instance illegal heart beat param before register.
-[#4593] Add server identity to replace user-agent white list.
-[#4662] Just choose one between nacosDomain mode and servers mode.

Refactor & Code Quality

-[#3831] Delete the old http client code.
-[#3832] Add common http client shutdown method.
-[#4093][#4125][#4310][#4346] Remove unused codes.
-[#4166] NotifyCenter code optimization.
-[#4225] Replace http client in HttpHealthCheckProcessor.
-[#4232] Use EnvUtil to replace ApplicationUtils about env operation.
-[#4293] Remove env operation code in ApplicationUtils.
-[#4275] Replace com.alibaba.nacos.config.server.result.ResultBuilder to RestResultUtil.
-[#4344] CacheMap property optimization.
-[#4567] Refactor nacos-client Load Logging Configuration code.
-[#4594][#4596] Fix IO close problem kind/code quality kind/refactor
-[#4631] Remove timer,Use ScheduledThreadPoolExecutor replaced.

BugFix

-[#3005] Fix ClusterController 403 and some display wrong.
-[#3406] Fix change self's password fail problem.
-[#3524][#4262] Fix public namespace permission problem.
-[#3880] NamingService Client support pushEmptyProtection.
-[#4073] Fix the problem for config default time zone may be wrong.
-[#4136] Fix ServiceInfo cann't correctlly instantiate from cache file.
-[#4181] Fix Auth may not work if contextPath is '/'.
-[#4187] Fix ProtocolManager#onEvent can't feel nodes extend.
-[#4199] Fix new http client do not support patch method problem.
-[#4236] Fix ProtocolException for apache http client Content-Length.
-[#4245] Fix sql injection bug.
-[#4264] Fix always load property when the contextPath is '/'.
-[#4282] Fix Service list Cannot query by group name.
-[#4311] Fix an exception will occur if the SQL include LIMIT, when use embedded data source.
-[#4320] Fix the Naming consistency module could not start in cluster mode.
-[#4333] Fix PaginationHelper will be abnormal in cluster mode.
-[#4342] Fix nacos.core.protocol.raft.data.read_index_type isn't effect.
-[#4364] Fix Cluster member state isn't updated to 'DOWN' after the node becomes down.
-[#4415] Fix NOW_WATCH_JOB_CNT record WatchDirJob count error.
-[#4424] Fixed issue where null values could not be converted to base parameters.
-[#4429] Fix mcp can't be open.
-[#4436] Fix parse label expression error problem.
-[#4450] Fix memberAddressInfos do not record Up State when member status updated.
-[#4467] Fix instanceId will be replaced when register twice.
-[#4477] Fix service list return error information if fromIndex > toIndex.
-[#4541][#4556] Fix the configuration file loading issue.
-[#4570] Fix cluster mode query config type is null.
-[#4583] Fix nacos client do not retry in DOMAIN mode.
-[#4643] Fix jraft response instance error.
-[#4701] Fix bypass authentication(identity) problem.

Other

-[#3102] Remove apache commons-lang3 dependency.
-[#4179] Add index for db.user and db.password.
-[#4339] Upgrade jraft to 1.3.5.
-[#4476] Update hint words in config list Fuzzy query.
-[#4632] Upgrade axios version to 0.21.1.