No i'm not seeing any errors.
One of these certificates is self-signed, but the ca and the certificate itself was added in the other owncloud-server and in the pakage ca-certificates.
when i turn on the loglevel to debugging i'm getting this message on server 2 from the owncloud.log:
cron.php
{"reqId":"4n1HQrUlwQgmjAgwtBq2","remoteAddr":"","app":"cli","message":"Memcache \OC\Memcache\APCu not available for local cache","level":1,"time":"2017-10-09T13:59:28+00:00","method":"--","url":"--","user":"--"}
{"reqId":"4n1HQrUlwQgmjAgwtBq2","remoteAddr":"","app":"cli","message":"Memcache \OC\Memcache\APCu not available for distributed cache","level":1,"time":"2017-10-09T13:59:28+00:00","method":"--","url":"--","user":"--"}
{"reqId":"4n1HQrUlwQgmjAgwtBq2","remoteAddr":"","app":"cron","message":"Started background job of class : OCA\Files\BackgroundJob\CleanupFileLocks with arguments : ","level":0,"time":"2017-10-09T13:59:28+00:00","method":"--","url":"--","user":"--"}
{"reqId":"4n1HQrUlwQgmjAgwtBq2","remoteAddr":"","app":"cron","message":"Finished background job, the job took : 0 seconds, this job is an instance of class : OCA\Files\BackgroundJob\CleanupFileLocks with arguments : ","level":0,"time":"2017-10-09T13:59:28+00:00","method":"--","url":"--","user":"--"}
{"reqId":"4n1HQrUlwQgmjAgwtBq2","remoteAddr":"","app":"cron","message":"Started background job of class : OCA\Files\BackgroundJob\ScanFiles with arguments : ","level":0,"time":"2017-10-09T13:59:28+00:00","method":"--","url":"--","user":"--"}
{"reqId":"4n1HQrUlwQgmjAgwtBq2","remoteAddr":"","app":"OC\Files\Cache\Scanner","message":"!!! Path '' is not accessible or present !!!","level":0,"time":"2017-10-09T13:59:29+00:00","method":"--","url":"--","user":"--"}
{"reqId":"4n1HQrUlwQgmjAgwtBq2","remoteAddr":"","app":"cron","message":"Finished background job, the job took : 1 seconds, this job is an instance of class : OCA\Files\BackgroundJob\ScanFiles with arguments : ","level":0,"time":"2017-10-09T13:59:29+00:00","method":"--","url":"--","user":"--"}
{"reqId":"4n1HQrUlwQgmjAgwtBq2","remoteAddr":"","app":"cron","message":"Started background job of class : OC\BackgroundJob\Legacy\RegularJob with arguments : Array\n(\n [0] => \OC\Files\Cache\BackgroundWatcher\n [1] => checkNext\n)\n","level":0,"time":"2017-10-09T13:59:29+00:00","method":"--","url":"--","user":"--"}
{"reqId":"4n1HQrUlwQgmjAgwtBq2","remoteAddr":"","app":"cron","message":"Finished background job, the job took : 0 seconds, this job is an instance of class : OC\BackgroundJob\Legacy\RegularJob with arguments : Array\n(\n [0] => \OC\Files\Cache\BackgroundWatcher\n [1] => checkNext\n)\n","level":0,"time":"2017-10-09T13:59:29+00:00","method":"--","url":"--","user":"--"}
{"reqId":"4n1HQrUlwQgmjAgwtBq2","remoteAddr":"","app":"cron","message":"Started background job of class : OC\Authentication\Token\DefaultTokenCleanupJob with arguments : ","level":0,"time":"2017-10-09T13:59:29+00:00","method":"--","url":"--","user":"--"}
{"reqId":"4n1HQrUlwQgmjAgwtBq2","remoteAddr":"","app":"no app in context","message":"Invalidating tokens older than 2017-10-08T13:59:29+00:00","level":1,"time":"2017-10-09T13:59:29+00:00","method":"--","url":"--","user":"--"}
{"reqId":"4n1HQrUlwQgmjAgwtBq2","remoteAddr":"","app":"cron","message":"Finished background job, the job took : 0 seconds, this job is an instance of class : OC\Authentication\Token\DefaultTokenCleanupJob with arguments : ","level":0,"time":"2017-10-09T13:59:29+00:00","method":"--","url":"--","user":"--"}
{"reqId":"4n1HQrUlwQgmjAgwtBq2","remoteAddr":"","app":"cron","message":"Started background job of class : OCA\Files_Sharing\DeleteOrphanedSharesJob with arguments : ","level":0,"time":"2017-10-09T13:59:29+00:00","method":"--","url":"--","user":"--"}
{"reqId":"4n1HQrUlwQgmjAgwtBq2","remoteAddr":"","app":"DeleteOrphanedSharesJob","message":"0 orphaned share(s) deleted","level":0,"time":"2017-10-09T13:59:29+00:00","method":"--","url":"--","user":"--"}
{"reqId":"4n1HQrUlwQgmjAgwtBq2","remoteAddr":"","app":"cron","message":"Finished background job, the job took : 0 seconds, this job is an instance of class : OCA\Files_Sharing\DeleteOrphanedSharesJob with arguments : ","level":0,"time":"2017-10-09T13:59:29+00:00","method":"--","url":"--","user":"--"}
{"reqId":"4n1HQrUlwQgmjAgwtBq2","remoteAddr":"","app":"cron","message":"Started background job of class : OCA\Activity\BackgroundJob\EmailNotification with arguments : ","level":0,"time":"2017-10-09T13:59:29+00:00","method":"--","url":"--","user":"--"}
{"reqId":"4n1HQrUlwQgmjAgwtBq2","remoteAddr":"","app":"cron","message":"Finished background job, the job took : 0 seconds, this job is an instance of class : OCA\Activity\BackgroundJob\EmailNotification with arguments : ","level":0,"time":"2017-10-09T13:59:29+00:00","method":"--","url":"--","user":"--"}
dav:sync-system-addressbook
{"reqId":"mq1Diw6T4YLK7uzxB8ej","remoteAddr":"","app":"cli","message":"Memcache \OC\Memcache\APCu not available for local cache","level":1,"time":"2017-10-09T13:59:50+00:00","method":"--","url":"--","user":"--"}
{"reqId":"mq1Diw6T4YLK7uzxB8ej","remoteAddr":"","app":"cli","message":"Memcache \OC\Memcache\APCu not available for distributed cache","level":1,"time":"2017-10-09T13:59:50+00:00","method":"--","url":"--","user":"--"}
federation:sync-adressbooks
{"reqId":"PNYXkorjn2xkA7RuLghh","remoteAddr":"","app":"cli","message":"Memcache \OC\Memcache\APCu not available for distributed cache","level":1,"time":"2017-10-09T13:37:30+00:00","method":"--","url":"--","user":"--"}
and on server 1 (has self signed certificate):
cron.php
{"reqId":"PtD6k9sGm1gdcnm1z4xS","remoteAddr":"","app":"cli","message":"Memcache \OC\Memcache\APCu not available for local cache","level":1,"time":"2017-10-09T14:01:14+00:00","method":"--","url":"--","user":"--"}
{"reqId":"PtD6k9sGm1gdcnm1z4xS","remoteAddr":"","app":"cli","message":"Memcache \OC\Memcache\APCu not available for distributed cache","level":1,"time":"2017-10-09T14:01:14+00:00","method":"--","url":"--","user":"--"}
{"reqId":"PtD6k9sGm1gdcnm1z4xS","remoteAddr":"","app":"cron","message":"Started background job of class : OCA\Files_Trashbin\BackgroundJob\ExpireTrash with arguments : ","level":0,"time":"2017-10-09T14:01:14+00:00","method":"--","url":"--","user":"--"}
{"reqId":"PtD6k9sGm1gdcnm1z4xS","remoteAddr":"","app":"cron","message":"Finished background job, the job took : 0 seconds, this job is an instance of class : OCA\Files_Trashbin\BackgroundJob\ExpireTrash with arguments : ","level":0,"time":"2017-10-09T14:01:14+00:00","method":"--","url":"--","user":"--"}
{"reqId":"PtD6k9sGm1gdcnm1z4xS","remoteAddr":"","app":"cron","message":"Started background job of class : OC\Authentication\Token\DefaultTokenCleanupJob with arguments : ","level":0,"time":"2017-10-09T14:01:14+00:00","method":"--","url":"--","user":"--"}
{"reqId":"PtD6k9sGm1gdcnm1z4xS","remoteAddr":"","app":"no app in context","message":"Invalidating tokens older than 2017-10-08T14:01:14+00:00","level":1,"time":"2017-10-09T14:01:14+00:00","method":"--","url":"--","user":"--"}
{"reqId":"PtD6k9sGm1gdcnm1z4xS","remoteAddr":"","app":"cron","message":"Finished background job, the job took : 0 seconds, this job is an instance of class : OC\Authentication\Token\DefaultTokenCleanupJob with arguments : ","level":0,"time":"2017-10-09T14:01:14+00:00","method":"--","url":"--","user":"--"}
{"reqId":"PtD6k9sGm1gdcnm1z4xS","remoteAddr":"","app":"cron","message":"Started background job of class : OCA\User_LDAP\Jobs\UpdateGroups with arguments : ","level":0,"time":"2017-10-09T14:01:14+00:00","method":"--","url":"--","user":"--"}
[I deleted LDAp notifications]
{"reqId":"PtD6k9sGm1gdcnm1z4xS","remoteAddr":"","app":"cron","message":"Finished background job, the job took : 0 seconds, this job is an instance of class : OCA\User_LDAP\Jobs\UpdateGroups with arguments : ","level":0,"time":"2017-10-09T14:01:14+00:00","method":"--","url":"--","user":"--"}
dav:sync-system-addressbook
{"reqId":"IUoG3RHjb8lGutBTsy+R","remoteAddr":"","app":"cli","message":"Memcache \OC\Memcache\APCu not available for local cache","level":1,"time":"2017-10-09T13:48:27+00:00","method":"--","url":"--","user":"--"}
{"reqId":"IUoG3RHjb8lGutBTsy+R","remoteAddr":"","app":"cli","message":"Memcache \OC\Memcache\APCu not available for distributed cache","level":1,"time":"2017-10-09T13:48:27+00:00","method":"--","url":"--","user":"--"}
[I deleted the ldap notifications]
{"reqId":"JsGEPVbM6Ojgo1HIRPHx","remoteAddr":"","app":"cli","message":"Memcache \OC\Memcache\APCu not available for local cache","level":1,"time":"2017-10-09T13:49:19+00:00","method":"--","url":"--","user":"--"}
federation:sync-addressbooks
{"reqId":"JsGEPVbM6Ojgo1HIRPHx","remoteAddr":"","app":"cli","message":"Memcache \OC\Memcache\APCu not available for distributed cache","level":1,"time":"2017-10-09T13:49:19+00:00","method":"--","url":"--","user":"--"}
I think, everything looks ok?