DNS Cache module does not seems to handle properly DNS SRV records.
Opensips "dns cache" perform a lookup on mydomain.com.
The DNS answers : SRV gw1.mydomain.com and gw2.mydomain.com
Then Opensips perform an "A" query to "gw1.mydomain.com"
The DNS answers 22.214.171.124 for gw1.mydomain.com.
Finaly opensips forward the SIP request to 126.96.36.199
After that, on a new SIP request, Opensips continue to forward request directly to 188.8.131.52 (gw1.mydomain.com) and never trie to use gw2.mydomain.com
In my point of view, there is an issue in the DNS Cache module. Opensips should try randomly both mydomain.com SRV records gw1.mydomain.com and gw2.mydomain.com