domain name system – BIND9 SERVFAIL using dig on the server UBUNTU 18


I am setting up a nextcloud + onlyoffice server on the Ubuntu 18 server and a local DNS network for my desktop.
I am not a real computer scientist, but I am tutorials and I read forums. Moreover, being in China, I do not have Google and most of my research finds irrelevant answers … I've seen many people who had a similar error to mine but no solution did not work for me. I'm sure it's an obvious but stupid mistake, but since I'm not familiar with the BIND9 syntax, I just do not see it …
here is my named.conf.local :

                zone "platform.local" IN {
master type;
file "/etc/bind/zones/db.platform.local";
//allow-transfer{211.66.139.29;};
allow-update {none; };
allow-query {any; };
};

zone "139.66.211.in-addr-arpa" IN {
master type;
file "/etc/bind/zones/db.rev.platform.local";
allow-update {none;};
};

my db.plateforme.local :

;
; BIND data file for local loopback interface
;
$ TTL 604800
@ IN SOA ns.plateform.local. root.plateforme.local. (
33; Serial
604800; Refresh
86400; try again
2419200; Expire
604800); TTL negative cover
;

; name servers - NS info
NS ns.plateform.local.

; name servers - address
ns IN A 211.66.139.29

; name servers - A records
nextcloud IN A 211.66.139.29
onlyoffice IN A 211.66.139.29

here is db.rev.plateforme.local :

;
; BIND inverted data file for local loopback interface
;
$ TTL 604800
@ IN SOA ns.plateform.local. root.plateforme.local. (
17; Serial
604800; Refresh
86400; try again
2419200; Expire
604800); TTL negative cover
;

; name servers - NS info
IN NS ns.plateform.local.
IN NS localhost.

; name servers - address
29 IN NS ns.plateform.local.

29 IN PTR nextcloud.plateform.
29 IN PTR onlyoffice.plateform.local.

Here is the result of dig nextcloud.plateform.local :

nextcloud @ nextcloud-server: / etc / bind / zones $ dig nextcloud.platform.local.
; << >> DiG 9.11.4-3ubuntu5.1-Ubuntu << >> nextcloud.plateforme.local.
;; global options: + cmd
;; Do you have the answer:
;; CAUTION: .local is reserved for multicast DNS
;; You are currently testing what happens when an mDNS query is filtered to DNS
;; - >> HEADER << - opcode: QUERY, status: SERVFAIL, id: 42787
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1

;; PSEUDOSECTION OPT:
; EDNS: version: 0, flags:; PNU: 65494
;; SECTION QUESTION:
; nextcloud.plateforme.local. IN ONE

;; Query time: 0 msec
;; SERVER: 127.0.0.53 # 53 (127.0.0.53)
;; WHEN: Tue 12 Mar 10:25:52 HKT 2019
;; MSG SIZE rcvd: 55

and the reverse dig dig -x 211.66.139.29 it works surprisingly:

nextcloud @ nextcloud-server: / etc / bind / zones $ dig -x 211.66.139.29

; << >> DiG 9.11.4-3ubuntu5.1-Ubuntu << >> -x 211.66.139.29
;; global options: + cmd
;; Do you have the answer:
;; - >> HEADER << - opcode: QUERY, status: NOERROR, id: 63404
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1

;; PSEUDOSECTION OPT:
; EDNS: version: 0, flags:; PNU: 65494
;; SECTION QUESTION:
; 29.139.66.211.in-addr.arpa. IN PTR

;; SECTION RESPONSE:
29.139.66.211.in-addr.arpa. 0 IN PTR nextcloud-server.
29.139.66.211.in-addr.arpa. 0 IN PTR nextcloud-server.local.

;; Time of interrogation: 120 ms
;; SERVER: 127.0.0.53 # 53 (127.0.0.53)
;; WHEN: Tue, Mar 12 10:39:53 HKT 2019
;; MSG SIZE rcvd: 121

I would be very grateful if anyone could help me … I set up this server for our team of 16 teachers because I took computer training more than ten years ago, because we we need this server and the supply on the continent. China is limited and out of reach … but I do it in addition to my teaching duties and it takes a lot of time. I would greatly appreciate the help and advice of experts.
Thank you in advance for your time!