Roon server slow to discover devices and critical error in server log

I have a problem with Roon in that it is very slow to detect new devices and or that devices is turned off.
My setup is Roon server on a Ubuntu 18.04 server installed with your shell script
My endpoints is a mixture of Sonos devices, A mobile phone and a Ropieee with a Hifiberry DAC+XLR HAT.
When i turn on the Ropieee it boots up fine and I can reach it with through the webinterface but it takes approx 30 minutes before the Roon server show the new endpoint throught the client and i can start playing music. Earlier i was able to play music on a endpoint 2 - 3minutes after it was turned on.

As a test i tried to turn off my Sonos devices to see if the problem was the same with these. After 20 minutes the Roon client stiil shows the turned off endpoints but I can select it for playing music. If i try to select “play” The client returnes “Roon cannot control the device”.

I have looked at the RoonServer_log.txt. It states an error (critical) but i am not able to interpretate it:

12/15 09:01:00 Critical: scx: in OnExit: System.NullReferenceException: Object reference not set to an instance of an object
  at Sooloos.Broker.RoonApi.TransportService_2.EndpointToJson (Sooloos.Broker.Api.Endpoint ep) [0x00028] in <1295ddc8c6aa41c3af1d916e70716b94>:0 
  at Sooloos.Broker.RoonApi.TransportService_2.<ZoneToJson>b__37_3 (Sooloos.Broker.Api.Endpoint x) [0x00000] in <1295ddc8c6aa41c3af1d916e70716b94>:0 
  at System.Linq.Enumerable+SelectListIterator`2[TSource,TResult].MoveNext () [0x00048] in <96d379be2b7a479fa5533b507b764d79>:0 
  at System.Collections.Generic.List`1[T].AddEnumerable (System.Collections.Generic.IEnumerable`1[T] enumerable) [0x00059] in <a30839b90db8462496ce6fa9ed772a6f>:0 
  at System.Collections.Generic.List`1[T]..ctor (System.Collections.Generic.IEnumerable`1[T] collection) [0x00062] in <a30839b90db8462496ce6fa9ed772a6f>:0 
  at Base.JList..ctor (System.Collections.Generic.IEnumerable`1[T] l) [0x00000] in <d6a3f6e62d51456e89dbc14d64b96781>:0 
  at Sooloos.Broker.RoonApi.TransportService_2.ZoneToJson (Sooloos.Broker.Api.Zone zone, System.Boolean for_diff) [0x00106] in <1295ddc8c6aa41c3af1d916e70716b94>:0 
  at Sooloos.Broker.RoonApi.TransportService_2._ActuallyChanged (Sooloos.Broker.Api.Zone zone) [0x00000] in <1295ddc8c6aa41c3af1d916e70716b94>:0 
  at Sooloos.Broker.RoonApi.TransportService_2.<_update_subscriptions>b__25_0 (Sooloos.Broker.Api.Zone x) [0x00000] in <1295ddc8c6aa41c3af1d916e70716b94>:0 
  at System.Linq.Enumerable+WhereEnumerableIterator`1[TSource].ToList () [0x0001b] in <96d379be2b7a479fa5533b507b764d79>:0 
  at System.Linq.Enumerable.ToList[TSource] (System.Collections.Generic.IEnumerable`1[T] source) [0x0001f] in <96d379be2b7a479fa5533b507b764d79>:0 
  at Sooloos.Broker.RoonApi.TransportService_2._update_subscriptions () [0x000db] in <1295ddc8c6aa41c3af1d916e70716b94>:0 
  at Sooloos.Broker.RoonApi.TransportService_2.OnThreadExit () [0x00034] in <1295ddc8c6aa41c3af1d916e70716b94>:0 
  at Sooloos.Broker.RoonApi.Module.ev_exit () [0x0000b] in <1295ddc8c6aa41c3af1d916e70716b94>:0 
  at Sooloos.SynchronizationContextThread.OnExit () [0x0000a] in <5477466545d54656a739f37f07f53905>:0

I tried to restart the RonnServer proces (systemctl restart roonserver.service)
Everything seems to start normally but now it discovers that the sonos zones was turned off. If I turn a Sonos zone on it appears in the Clinet after a minute or two as expected. But the Ropieee client does still not appear 15 minutes after restart of the server process.
The Ropieee is at 192.168.1.107 and has a Rpi display attached.
I have found this in the server logs - if it’s relevant:

12/15 09:24:13 Trace: [dbperf] flush 0 bytes, 0 ops in 1 ms (cumulative 9770319 bytes, 5134 ops in 29419 ms)
12/15 09:24:14 Debug: [easyhttp] [49] POST to https://metadata.roonlabs.net/1/albums/translate?c=tidal-dk returned after 214 ms, status code: 200
12/15 09:24:14 Info: [library/albumdetails] found 3 streaming service alternates
12/15 09:24:14 Debug: [easyhttp] [50] POST to https://metadata.roonlabs.net/1/works/translate?c=tidal-dk returned after 301 ms, status code: 200
12/15 09:24:25 Info: [stats] 1792mb Virtual, 931mb Physical, 446mb Managed, 0 Handles, 56 Threads
12/15 09:24:28 Trace: [roonapi] [apiclient 192.168.1.107:48976] CONTINUE Changed {"message":"Running (8)","is_error":false}
12/15 09:24:40 Info: [stats] 1792mb Virtual, 931mb Physical, 446mb Managed, 0 Handles, 56 Threads
^C
root@roon-server:/var/roon/RoonServer/Logs# 12/15 09:01:00 Critical: scx: in OnExit: System.NullReferenceException: Object reference not set to an instance of an object
-bash: 12/15: No such file or directory
root@roon-server:/var/roon/RoonServer/Logs#   at Sooloos.Broker.RoonApi.TransportService_2.EndpointToJson (Sooloos.Broker.Api.Endpoint ep) [0x00028] in <1295ddc8c6aa41c3af1d916e70716b94>:0 
-bash: syntax error near unexpected token `('
root@roon-server:/var/roon/RoonServer/Logs#   at Sooloos.Broker.RoonApi.TransportService_2.<ZoneToJson>b__37_3 (Sooloos.Broker.Api.Endpoint x) [0x00000] in <1295ddc8c6aa41c3af1d916e70716b94>:0 
-bash: syntax error near unexpected token `('
root@roon-server:/var/roon/RoonServer/Logs#   at System.Linq.Enumerable+SelectListIterator`2[TSource,TResult].MoveNext () [0x00048] in <96d379be2b7a479fa5533b507b764d79>:0 
>   at System.Collections.Generic.List`1[T].AddEnumerable (System.Collections.Generic.IEnumerable`1[T] enumerable) [0x00059] in <a30839b90db8462496ce6fa9ed772a6f>:0 
-bash: syntax error near unexpected token `('
root@roon-server:/var/roon/RoonServer/Logs#   at System.Collections.Generic.List`1[T]..ctor (System.Collections.Generic.IEnumerable`1[T] collection) [0x00062] in <a30839b90db8462496ce6fa9ed772a6f>:0 
-bash: syntax error near unexpected token `)'
root@roon-server:/var/roon/RoonServer/Logs#   at Base.JList..ctor (System.Collections.Generic.IEnumerable`1[T] l) [0x00000] in <d6a3f6e62d51456e89dbc14d64b96781>:0 
-bash: syntax error near unexpected token `('
root@roon-server:/var/roon/RoonServer/Logs#   at Sooloos.Broker.RoonApi.TransportService_2.ZoneToJson (Sooloos.Broker.Api.Zone zone, System.Boolean for_diff) [0x00106] in <1295ddc8c6aa41c3af1d916e70716b94>:0 
-bash: syntax error near unexpected token `('
root@roon-server:/var/roon/RoonServer/Logs#   at Sooloos.Broker.RoonApi.TransportService_2._ActuallyChanged (Sooloos.Broker.Api.Zone zone) [0x00000] in <1295ddc8c6aa41c3af1d916e70716b94>:0 
-bash: syntax error near unexpected token `('
root@roon-server:/var/roon/RoonServer/Logs#   at Sooloos.Broker.RoonApi.TransportService_2.<_update_subscriptions>b__25_0 (Sooloos.Broker.Api.Zone x) [0x00000] in <1295ddc8c6aa41c3af1d916e70716b94>:0 
-bash: syntax error near unexpected token `('
root@roon-server:/var/roon/RoonServer/Logs#   at System.Linq.Enumerable+WhereEnumerableIterator`1[TSource].ToList () [0x0001b] in <96d379be2b7a479fa5533b507b764d79>:0 
>   at System.Linq.Enumerable.ToList[TSource] (System.Collections.Generic.IEnumerable`1[T] source) [0x0001f] in <96d379be2b7a479fa5533b507b764d79>:0 
-bash: syntax error near unexpected token `)'
root@roon-server:/var/roon/RoonServer/Logs#   at Sooloos.Broker.RoonApi.TransportService_2._update_subscriptions () [0x000db] in <1295ddc8c6aa41c3af1d916e70716b94>:0 
-bash: syntax error near unexpected token `('
root@roon-server:/var/roon/RoonServer/Logs#   at Sooloos.Broker.RoonApi.TransportService_2.OnThreadExit () [0x00034] in <1295ddc8c6aa41c3af1d916e70716b94>:0 
-bash: syntax error near unexpected token `('
root@roon-server:/var/roon/RoonServer/Logs#   at Sooloos.Broker.RoonApi.Module.ev_exit () [0x0000b] in <1295ddc8c6aa41c3af1d916e70716b94>:0 
-bash: syntax error near unexpected token `('
root@roon-server:/var/roon/RoonServer/Logs#   at Sooloos.SynchronizationContextThread.OnExit () [0x0000a] in <5477466545d54656a739f37f07f53905>:0 
-bash: syntax error near unexpected token

I found the error. IT was the Ropieee version 3.015 that did not work when a display was attached to the Rpi 2B.
Without the display everything works ok