Description of problem:
Getting client connection error after starting volume. This is not affecting in the working of Gluster MOunts. But seeing a number of error messages in glustershd.log and the <mount>.log in the client.
I am running GLuster FS on RHEL 7.5 on Azure VMs

Version-Release number of selected component (if applicable):
glusterfs 4.1.5

How reproducible:
Create a volume, start it and mount from a client


Steps to Reproduce:
1.Create a volume
2. Start it 
3. MOunt on a client

Actual results:
Everything working fine, except for the error messages in logs

[2019-02-12 12:13:52.208065] W [rpc-clnt.c:1753:rpc_clnt_submit] 0-testvol2-client-3: error returned while attempting to connect to host:(null), port:0
[2019-02-12 12:13:52.208287] I [MSGID: 114046] [client-handshake.c:1176:client_setvolume_cbk] 0-testvol2-client-1: Connected to testvol2-client-1, attached to remote volume '/data/brick1/testvol2/brk1'.
[2019-02-12 12:13:52.208312] I [MSGID: 108005] [afr-common.c:5336:__afr_handle_child_up_event] 0-testvol2-replicate-0: Subvolume 'testvol2-client-1' came back up; going online.
[2019-02-12 12:13:52.208411] W [rpc-clnt.c:1753:rpc_clnt_submit] 0-testvol2-client-3: error returned while attempting to connect to host:(null), port:0
[2019-02-12 12:13:52.208593] I [rpc-clnt.c:2105:rpc_clnt_reconfig] 0-testvol2-client-3: changing port to 49153 (from 0)
[2019-02-12 12:13:52.213669] W [rpc-clnt.c:1753:rpc_clnt_submit] 0-testvol2-client-3: error returned while attempting to connect to host:(null), port:0
[2019-02-12 12:13:52.213969] W [rpc-clnt.c:1753:rpc_clnt_submit] 0-testvol2-client-3: error returned while attempting to connect to host:(null), port:0
[2019-02-12 12:13:52.217485] I [MSGID: 114046] [client-handshake.c:1176:client_setvolume_cbk] 0-testvol2-client-3: Connected to testvol2-client-3, attached to remote volume '/data/brick1/testvol2/brk2'.
[2019-02-12 12:13:52.217527] I [MSGID: 108005] [afr-common.c:5336:__afr_handle_child_up_event] 0-testvol2-replicate-1: Subvolume 'testvol2-client-3' came back up; going online.
[2019-02-12 12:13:55.516893] W [rpc-clnt.c:1753:rpc_clnt_submit] 0-testvol2-client-0: error returned while attempting to connect to host:(null), port:0
[2019-02-12 12:13:55.517086] W [rpc-clnt.c:1753:rpc_clnt_submit] 0-testvol2-client-0: error returned while attempting to connect to host:(null), port:0
[2019-02-12 12:13:55.517266] I [rpc-clnt.c:2105:rpc_clnt_reconfig] 0-testvol2-client-0: changing port to 49152 (from 0)
[2019-02-12 12:13:55.520686] W [rpc-clnt.c:1753:rpc_clnt_submit] 0-testvol2-client-2: error returned while attempting to connect to host:(null), port:0
[2019-02-12 12:13:55.520921] W [rpc-clnt.c:1753:rpc_clnt_submit] 0-testvol2-client-2: error returned while attempting to connect to host:(null), port:0
[2019-02-12 12:13:55.521055] I [rpc-clnt.c:2105:rpc_clnt_reconfig] 0-testvol2-client-2: changing port to 49153 (from 0)
[2019-02-12 12:13:55.523566] W [rpc-clnt.c:1753:rpc_clnt_submit] 0-testvol2-client-0: error returned while attempting to connect to host:(null), port:0
[2019-02-12 12:13:55.523819] W [rpc-clnt.c:1753:rpc_clnt_submit] 0-testvol2-client-0: error returned while attempting to connect to host:(null), port:0
[2019-02-12 12:13:55.525572] I [MSGID: 114046] [client-handshake.c:1176:client_setvolume_cbk] 0-testvol2-client-0: Connected to testvol2-client-0, attached to remote volume '/data/brick1/testvol2/brk1'.
[2019-02-12 12:13:55.526418] W [rpc-clnt.c:1753:rpc_clnt_submit] 0-testvol2-client-2: error returned while attempting to connect to host:(null), port:0
[2019-02-12 12:13:55.526616] W [rpc-clnt.c:1753:rpc_clnt_submit] 0-testvol2-client-2: error returned while attempting to connect to host:(null), port:0
[2019-02-12 12:13:55.534983] I [MSGID: 114046] [client-handshake.c:1176:client_setvolume_cbk] 0-testvol2-client-2: Connected to testvol2-client-2, attached to remote volume '/data/brick1/testvol2/brk2'.

Expected results:


Additional info:
I am able to see these errors in brick logs also at times