Load balancing weights have no effect

I want to config upstream and target for balancing my traffic
just like
Upstream name: service.v1
Target 1 : XXX 20
Target 2 : XXX 80

algorithm is round-robin, slots is 100.
but I found when ‘xxx’ is host:port, the proportion of traffic is split in half.
when ‘xxx’ ip: port, the flow ratio is normal.
I want to use host:port this format goes to load balancing, anyone can help me???