UI logs showing multiple errors, (XDCR bi and uni, at the start of a rebalance-in operation): Server error during processing: ["web request failed" ...

+ 5 nodes rebalance in on each cluster
Cluster setup: c1:c2::10:10
biXDCR_bucket: c1 <---> c2
uniXDCR_src: c1 ---> c2 :uniXDCR_dest
Front end loads on c1 and c2 for biXDCR_bucket, and on c1 for uniXDCR_src.
c1: http://ec2-177-71-230-72.sa-east-1.compute.amazonaws.com:8091/
c2: http://ec2-175-41-186-167.ap-southeast-1.compute.amazonaws.com:8091/

UI reports whole bunch of these errors at the start of rebalancing operation and with the front end loads:
Server error during processing: ["web request failed",
{path,"/pools/default"},
{type,exit},
{what,
{timeout,
{gen_server,call,
[ns_doctor,get_tasks_version]}}},
{trace,
[{gen_server,call,2},
{menelaus_web,build_pool_info,4},
{menelaus_web,handle_pool_info_wait,5},
{menelaus_web,loop,3},
{mochiweb_http,headers,5},
{proc_lib,init_p_do_apply,3}]}] (repeated 1 times)

Will attach grabbed diags from the particular server in a bit.