736807:20220413:071815.316 Unable to connect to [internal-company.domain]:10051 [cannot connect to [[internal-company.domain]:10051]: [111] Connection refused]

connection refused, i also got same when i was doing setup almost like this, by setting ipv6 in place of 'internal-company.domain' it works fine, because ipv4 was not enabled in my kubernetes setup, for solving your issue, setting ipv6 in DNS record for 'internal-company.domain' it might work.