Routing with Relative URI

My client used our container platform for microgateway by SoftwareAG. There is a neccesity so that the base URI that passed into service is using relative URI.

Normally, it works like this:

things that added in routes:
https://microgateway-service-a.container.com
it might open:
[*] https://microgateway-service-a.container.com/rest/microgateway/status

but when we changed the routes into this:
https://microgateway.container.com/service-a

we can't open the similar [*] menu:
https://microgateway.container.com/service-a/rest/microgateway/status

"/rest/microgateway/status" is the built in rest api on microgateway platform. How should we configure so that service only recognize /rest/microgateway/status not the "service-a" from routing configuration. I thought initially, relative uri pass through the service will ignore the relative URI written in routing configuration.

Any kind advice from community, any help will be appreciated. thx