I have seen this a couple of times, but not enough to write a bug report. For some reason, DNS / resolver doesn't work initially.
Try to ping pkg.freebsd.org before starting with pkg. Like thisping pkg.freebsd.org
That helped for me.
I have no problem with my android. I have access to pkg.freebsd.orgMay be it is a temporary error. It seems that the host name could not be resolved. I have opened the link in a browser and I could see packagesite.txz.