thank you so much for all the above!
I have followed your instructions and have come so far here:

  • changed port to 27017 (checked firewall status also)

  • checked ownership of /var/lib/mongodb . Is it worrying that the permissions are not all the same of all the files included?

ls -l /var/lib/mongodb
total 38488
-rw------- 1 mongodb mongodb    36864 Μάρ  22 00:04 collection-0-2356690320700739995.wt
-rw------- 1 mongodb mongodb 36732928 Μάρ  22 00:04 collection-0-5563536140699528517.wt
-rw------- 1 mongodb mongodb    40960 Μάρ  22 00:04 collection-10-5563536140699528517.wt
-rw------- 1 mongodb mongodb   184320 Μάρ  22 00:04 collection-12-5563536140699528517.wt
-rw------- 1 mongodb mongodb    36864 Μάρ  22 00:04 collection-14-5563536140699528517.wt
-rw------- 1 mongodb mongodb   532480 Μάρ  22 00:04 collection-20-5563536140699528517.wt
-rw------- 1 mongodb mongodb    36864 Μάρ  22 00:04 collection-2-2356690320700739995.wt
-rw------- 1 mongodb mongodb   307200 Μάρ  22 00:04 collection-2-5563536140699528517.wt
-rw------- 1 mongodb mongodb    24576 Μάρ  22 00:04 collection-4-2356690320700739995.wt
-rw------- 1 mongodb mongodb   114688 Μάρ  22 00:04 collection-4-5563536140699528517.wt
-rw------- 1 mongodb mongodb   294912 Μάρ  22 00:04 collection-6-5563536140699528517.wt
-rw------- 1 mongodb mongodb    36864 Μάρ  22 00:04 collection-8-2356690320700739995.wt
-rw------- 1 mongodb mongodb   172032 Μάρ  22 00:04 collection-8-5563536140699528517.wt
drwx------ 2 mongodb mongodb     4096 Μάρ  21 23:26 diagnostic.data
-rw------- 1 mongodb mongodb    36864 Νοέ  17 10:42 index-10-2356690320700739995.wt
-rw------- 1 mongodb mongodb    24576 Νοέ  17 12:02 index-11-5563536140699528517.wt
-rw------- 1 mongodb mongodb    36864 Μάρ  22 00:04 index-1-2356690320700739995.wt
-rw------- 1 mongodb mongodb    24576 Νοέ  17 12:02 index-13-5563536140699528517.wt
-rw------- 1 mongodb mongodb    36864 Νοέ  23 21:45 index-15-5563536140699528517.wt
-rw------- 1 mongodb mongodb   180224 Νοέ  17 11:55 index-1-5563536140699528517.wt
-rw------- 1 mongodb mongodb    49152 Νοέ  23 11:26 index-21-5563536140699528517.wt
-rw------- 1 mongodb mongodb    36864 Μάρ  22 00:04 index-3-2356690320700739995.wt
-rw------- 1 mongodb mongodb    49152 Νοέ  17 12:00 index-3-5563536140699528517.wt
-rw------- 1 mongodb mongodb    24576 Μάρ  22 00:04 index-5-2356690320700739995.wt
-rw------- 1 mongodb mongodb    20480 Νοέ  17 12:00 index-5-5563536140699528517.wt
-rw------- 1 mongodb mongodb    12288 Μάρ  22 00:04 index-6-2356690320700739995.wt
-rw------- 1 mongodb mongodb    49152 Νοέ  17 12:01 index-7-5563536140699528517.wt
-rw------- 1 mongodb mongodb    36864 Νοέ  17 10:41 index-9-2356690320700739995.wt
-rw------- 1 mongodb mongodb    53248 Νοέ  17 12:01 index-9-5563536140699528517.wt
drwx------ 2 mongodb mongodb     4096 Μάρ  29 17:45 journal
-rw------- 1 mongodb mongodb    36864 Μάρ  22 00:04 _mdb_catalog.wt
-rw------- 1 mongodb mongodb        0 Μάρ  27 20:50 mongod.lock
-rw------- 1 mongodb mongodb    36864 Μάρ  22 00:04 sizeStorer.wt
-rw------- 1 mongodb mongodb      114 Νοέ  16 21:08 storage.bson
-rw------- 1 mongodb mongodb       44 Νοέ  16 21:08 WiredTiger
-rw------- 1 mongodb mongodb     4096 Μάρ  21 23:26 WiredTigerLAS.wt
-rw------- 1 mongodb mongodb       21 Μάρ  27 20:50 WiredTiger.lock
-rw------- 1 mongodb mongodb     1190 Μάρ  22 00:04 WiredTiger.turtle
-rw------- 1 mongodb mongodb    73728 Μάρ  29 17:45 WiredTiger.wt
  • checked ownership of /var/log/mongodb
    -rw------- 1 mongodb mongodb 41533 Μάρ 29 17:45 /var/log/mongodb/mongod.log

  • used systemctl start mongod to start mongod

  • I tried vim /var/log/mongodb/mongod.log but got Permission denied,so I used sudo vim /var/log/mongodb/mongod.log and got the below:

2022-03-29T18:01:46.885+0300 I  CONTROL  [initandlisten] options: { config: "/etc/mongod.conf", net: { bindIp: "0.0.0.0", port: 27017 }, processManagement: { timeZoneInfo: "/usr/share/zoneinfo" }, security: { authorization: "enabled" }, storage: { dbPath: "/var/lib/mongodb", journal: { enabled: true } }, systemLog: { destination: "file", logAppend: true, path: "/var/log/mongodb/mongod.log" } }
2022-03-29T18:01:46.885+0300 I  STORAGE  [initandlisten] Detected data files in /var/lib/mongodb created by the 'wiredTiger' storage engine, so setting the active storage engine to 'wiredTiger'.
2022-03-29T18:01:46.885+0300 I  STORAGE  [initandlisten]
2022-03-29T18:01:46.885+0300 I  STORAGE  [initandlisten] ** WARNING: Using the XFS filesystem is strongly recommended with the WiredTiger storage engine
2022-03-29T18:01:46.885+0300 I  STORAGE  [initandlisten] **          See http://dochub.mongodb.org/core/prodnotes-filesystem
2022-03-29T18:01:46.885+0300 I  STORAGE  [initandlisten] wiredtiger_open config: create,cache_size=1463M,cache_overflow=(file_max=0M),session_max=33000,eviction=(threads_min=4,threads_max=4),config_base=false,statistics=(fast),log=(enabled=true,archive=true,path=journal,compressor=snappy),file_manager=(close_idle_time=100000),statistics_log=(wait=0),verbose=[recovery_progress,checkpoint_progress],
2022-03-29T18:01:48.128+0300 E  STORAGE  [initandlisten] WiredTiger error (2) [1648566108:128072][4214:0x7fc881fbcb00], txn-recover: __posix_open_file, 712: /var/lib/mongodb/journal/WiredTigerLog.0000000015: handle-open: open: No such file or directory Raw: [1648566108:128072][4214:0x7fc881fbcb00], txn-recover: __posix_open_file, 712: /var/lib/mongodb/journal/WiredTigerLog.0000000015: handle-open: open: No such file or directory
2022-03-29T18:01:48.128+0300 E  STORAGE  [initandlisten] WiredTiger error (2) [1648566108:128318][4214:0x7fc881fbcb00], txn-recover: __wt_log_scan, 2625: WiredTiger is unable to read the recovery log.: No such file or directory Raw: [1648566108:128318][4214:0x7fc881fbcb00], txn-recover: __wt_log_scan, 2625: WiredTiger is unable to read the recovery log.: No such file or directory
2022-03-29T18:01:48.128+0300 E  STORAGE  [initandlisten] WiredTiger error (2) [1648566108:128374][4214:0x7fc881fbcb00], txn-recover: __wt_log_scan, 2628: This may be due to the log files being encrypted, being from an older version or due to corruption on disk: No such file or directory Raw: [1648566108:128374][4214:0x7fc881fbcb00], txn-recover: __wt_log_scan, 2628: This may be due to the log files being encrypted, being from an older version or due to corruption on disk: No such file or directory
2022-03-29T18:01:48.128+0300 E  STORAGE  [initandlisten] WiredTiger error (2) [1648566108:128445][4214:0x7fc881fbcb00], txn-recover: __wt_log_scan, 2631: You should confirm that you have opened the database with the correct options including all encryption and compression options: No such file or directory Raw: [1648566108:128445][4214:0x7fc881fbcb00], txn-recover: __wt_log_scan, 2631: You should confirm that you have opened the database with the correct options including all encryption and compression options: No such file or directory
2022-03-29T18:01:48.128+0300 E  STORAGE  [initandlisten] WiredTiger error (-31802) [1648566108:128500][4214:0x7fc881fbcb00], txn-recover: __wt_txn_recover, 770: Recovery failed: WT_ERROR: non-specific WiredTiger error Raw: [1648566108:128500][4214:0x7fc881fbcb00], txn-recover: __wt_txn_recover, 770: Recovery failed: WT_ERROR: non-specific WiredTiger error
2022-03-29T18:01:48.143+0300 E  STORAGE  [initandlisten] WiredTiger error (0) [1648566108:143758][4214:0x7fc881fbcb00], connection: __wt_cache_destroy, 386: cache server: exiting with 1 pages in memory and 0 pages evicted Raw: [1648566108:143758][4214:0x7fc881fbcb00], connection: __wt_cache_destroy, 386: cache server: exiting with 1 pages in memory and 0 pages evicted
2022-03-29T18:01:48.143+0300 E  STORAGE  [initandlisten] WiredTiger error (0) [1648566108:143906][4214:0x7fc881fbcb00], connection: __wt_cache_destroy, 391: cache server: exiting with 78 image bytes in memory Raw: [1648566108:143906][4214:0x7fc881fbcb00], connection: __wt_cache_destroy, 391: cache server: exiting with 78 image bytes in memory
2022-03-29T18:01:48.143+0300 E  STORAGE  [initandlisten] WiredTiger error (0) [1648566108:143949][4214:0x7fc881fbcb00], connection: __wt_cache_destroy, 395: cache server: exiting with 302 bytes in memory Raw: [1648566108:143949][4214:0x7fc881fbcb00], connection: __wt_cache_destroy, 395: cache server: exiting with 302 bytes in memory

is there any other way to access logs without sudo?