Hi I am getting this error.
Root Cause(s):
Here is one conf presentation which you probably could use to check if there is local issue or where the issue could be.
https://conf.splunk.com/files/2019/slides/FN1570.pdf
Telnet will tell you if a network connection can be made, but won't say if the Splunk-to-Splunk protocol is working or not.
Have you confirmed all forwarders are running? Do they have the right outputs.conf settings? Are their certificates valid?
Have you looked at each forwarder's splunkd.log file to see what connection errors are being reported?
Do you replace forwarders often? If so, Splunk probably still expects to hear from the old ones and this message may be a false positive.