JWT Auth from Rocket.Chat sometime works... or not

Hello, I’m stuck with authentication.
Rocket-Chat on chat-example-com works and is hopefully properly configured for video with Jitsi-Meet-
Jitsi-Meet worked (jitsi-example-com) for everybody too- Since authentication is set to “token” - it works or not- I can’t find the reason, why sometimes I can talk with three users (with video) and sometimes I can’t create a room / join to room with “authentication error”.
A bit shorted prosody-log:
Apr 17 09:35:27 conference-jitsi-example-com:muc_domain_mapper warn Session filters applied
Apr 17 09:35:27 mod_bosh info New BOSH session, assigned it sid ‘42eb8734-5c30-4433-aef2-33bd1cdd0933’
Apr 17 09:35:27 general warn Error verifying token err:not-allowed, reason:Not acceptable by nbf
Apr 17 09:40:21 conference-jitsi-example-com:muc_domain_mapper warn Session filters applied
Apr 17 09:40:21 mod_bosh info New BOSH session, assigned it sid ‘3dcac02e-2bbf-4af6-83f7-0aa18942be4e’
Apr 17 09:40:21 bosh3dcac02e-2bbf-4af6-83f7-0aa18942be4e info Authenticated as 66835367-9793-4477-9f26-69ab243df70d@jitsi-example-com
Apr 17 09:40:29 bosh3dcac02e-2bbf-4af6-83f7-0aa18942be4e info BOSH client disconnected: session close
Apr 17 09:40:29 speakerstats-jitsi-example-com:speakerstats_component warn A module has been configured that triggers external events-
Apr 17 09:40:29 speakerstats-jitsi-example-com:speakerstats_component warn Implement this lib to trigger external events-
Apr 17 09:43:38 mod_bosh info Client tried to use sid ‘42eb8734-5c30-4433-aef2-33bd1cdd0933’ which we don’t know about
Apr 17 09:43:41 conference-jitsi-example-com:muc_domain_mapper warn Session filters applied
Apr 17 09:43:41 mod_bosh info New BOSH session, assigned it sid ‘63738514-ea3a-4122-a926-7b704a9e2c85’
Apr 17 09:43:41 general warn Error verifying token err:not-allowed, reason:Not acceptable by nbf
Apr 17 09:43:46 bosh63738514-ea3a-4122-a926-7b704a9e2c85 info BOSH client disconnected: session close
Apr 17 09:43:55 conference-jitsi-example-com:muc_domain_mapper warn Session filters applied
Apr 17 09:43:55 mod_bosh info New BOSH session, assigned it sid ‘485e506f-dd8f-475e-a62c-bc7d329ece73’
Apr 17 09:43:55 general warn Error verifying token err:not-allowed, reason:Not acceptable by nbf
Apr 17 09:44:01 bosh485e506f-dd8f-475e-a62c-bc7d329ece73 info BOSH client disconnected: session close
Apr 17 09:44:19 conference-jitsi-example-com:muc_domain_mapper warn Session filters applied
Apr 17 09:44:19 mod_bosh info New BOSH session, assigned it sid ‘90b31883-06c8-48b8-9a50-c1f0fc84d0b5’
Apr 17 09:44:19 general warn Error verifying token err:not-allowed, reason:Not acceptable by nbf
Apr 17 09:44:23 bosh90b31883-06c8-48b8-9a50-c1f0fc84d0b5 info BOSH client disconnected: session close
Apr 17 09:47:14 conference-jitsi-example-com:muc_domain_mapper warn Session filters applied
Apr 17 09:47:14 mod_bosh info New BOSH session, assigned it sid ‘76b8db74-4764-4f63-b93d-8d4dc5aef046’
Apr 17 09:47:14 general warn Error verifying token err:not-allowed, reason:Not acceptable by nbf
Apr 17 09:49:17 mod_bosh info Client tried to use sid ‘76b8db74-4764-4f63-b93d-8d4dc5aef046’ which we don’t know about
Apr 17 09:49:28 conference-jitsi-example-com:muc_domain_mapper warn Session filters applied
Apr 17 09:49:28 mod_bosh info New BOSH session, assigned it sid ‘feca981a-6df8-4813-9169-c51a2de75ef7’
Apr 17 09:49:28 boshfeca981a-6df8-4813-9169-c51a2de75ef7 info Authenticated as 88a24577-aabb-4e5d-910a-88821135d6ec@jitsi-example-com
Apr 17 09:50:56 conference-jitsi-example-com:muc_domain_mapper warn Session filters applied
Apr 17 09:50:56 mod_bosh info New BOSH session, assigned it sid ‘643557d0-7301-4533-b2ef-9f515d66df74’
Apr 17 09:50:56 general warn Error verifying token err:not-allowed, reason:Not acceptable by nbf
Apr 17 09:50:59 bosh643557d0-7301-4533-b2ef-9f515d66df74 info BOSH client disconnected: session close

Whats mean: “Not acceptable by nbf”?
Greets
PS. In all URLs dots swapped with “-” (I’m not allowed to post more than two URLs).

Hi.
I don’t know, how to add “solved” to topic, but this problem is solved.
The problem was 2.5 seconds system time difference between rocketchat and jitsi-server…

(“nbf” - “NotValidBefore”)
Greets