Problems with enabling collabora on nextcloud

Hello guys,

I have installed collabora on nextcloud, but I have problems with enabling it for users. When I open new document I get error and inside my server logs i see this:

[Sun Oct 07 19:51:04.065989 2018] [proxy:error] [pid 2749] AH00959: ap_proxy_connect_backend disabling worker for (localhost) for 0s
[Sun Oct 07 19:51:04.066035 2018] [proxy_http:error] [pid 2749] [client] AH01114: HTTP: failed to make connection to backend: localhost
[Sun Oct 07 19:51:25.138136 2018] [proxy:error] [pid 2749] (111)Connection refused: AH00957: HTTPS: attempt to connect to (localhost) failed

Can you please help me?

Thank you!