Getting NOSRV and MAINT while from container netns the backend server seems ok

Help!
1

Backend stays in MAINT and logs say "synapse~ synapse/ 0/-1/-1/-1/0 503 222 - - SC-- 3/1/0/0/0 0/0 “GET /_matrix/static/ HTTP/1.1"”

Where can I see what nameservers are being used by haproxy?
Should I add some time outs for getting new dns srv records?

haproxy.cfg has

resolvers dnssvrs1
  parse-resolv-conf
  hold valid 10s

backend synapse
  mode http
  balance roundrobin
  option forwardfor
  default-server check resolvers dnssvrs1
  server-template synapse 3 _https._synapse.dev._tcp.marathon.mesos weight 100 resolve-opts allow-dup-ip

While command line :

# dig +short srv _https._synapse.dev._tcp.marathon.mesos
0 1 31212 synapse.dev-7qz9q-s4.marathon.mesos.

I can also ping and open the backend server with lynx.