OS7 & OS5 X64 models how to disable the SMB1, thus please try on this method:

OS7
1. Please update to V3.02.00.2 or above version for SambaCry Vulnerability (CVE-2017-7494).
2. If NAS with Internet access capacity, it is no need to download this file from Thecus WEB site, just from NAS ADMIN WEB page: CONTROL PANEL -> CONTROL -> FIRMWARE SETTING -> AUTO UPGRADE.

OS5 X64

Method A
Please update to V2.06.02.10
http://www.thecus.com/Downloads/FW/64/Thecus_x86_64_FW.2.06.02.10.cdv_build9703_N2800_N4510U_N4800_N5550_N7510.rom
http://www.thecus.com/Downloads/FW/64/Thecus_x86_64_FW.2.06.02.10.v2_build9703_N7700PROV2_N8800PROV2.rom
http://www.thecus.com/Downloads/FW/64/Thecus_x86_64_FW.2.06.02.10_build9703_N5810_N7710_N7770_N8810_N8880_N6850_N8850_N10850_N8900_N12000_N12850_N16000_N16850.rom
System force disable SMB1, if your client devices unsupported SMB2 would re-enable the SMB1, you may re-enable from NAS ADMIN WEB page: HOME -> NETWORK SERVICE -> SAMBA/CIFS -> SMB Min Protocol -> LANMAN1

Method B
1. Download CONF.BIN as a backup, from [System Management/ Config Mgmt] and then press [Download] button.
2. Upload this patch, and no need to reboot.
3. Even after reboot and this patch is working still. If you would remove this patch, please reset to factory default an upload the CONF.BIN as step 1 saved.

* What is OS7 & OS5 X64 models: http://thecus.kayako.com/default_import/Knowledgebase/Article/View/606/0/thecus-raid-roaming-table