Hello.
I tested qos-scripts on omnii with wan interface. I set up upload and download speed to 1024 kbps.
The result is syslog errors:
2019-05-18 09:19:58 warning kernel[]: [76429.313498] ------------[ cut here ]------------
2019-05-18 09:19:58 warning kernel[]: [76429.313513] WARNING: CPU: 1 PID: 3129 at net/sched/sch_hfsc.c:1426 hfsc_dequeue+0x34c/0x508 [sch_hfsc]()
2019-05-18 09:19:58 warning kernel[]: [76429.313516] Modules linked in: ifb qcserial option iptable_nat ath9k usb_wwan rndis_host qmi_wwan pppoe nf_nat_pptp nf_nat_ipv4 nf_nat_amanda nf_conntrack_pptp nf_conntrack_ipv6 nf_conntrack_ipv4 nf_conntrack_amanda ipt_REJECT ipt_MASQUERADE ebtable_nat ebtable_filter ebtable_broute cdc_ether ath9k_common armada_thermal xt_time xt_tcpudp xt_tcpmss xt_statistic xt_state xt_recent xt_quota xt_pkttype xt_physdev xt_owner xt_nat xt_multiport xt_mark xt_mac xt_limit xt_length xt_id xt_hl xt_helper xt_ecn xt_dscp xt_conntrack xt_connmark xt_connlimit xt_connbytes xt_comment xt_addrtype xt_TCPMSS xt_REDIRECT xt_LOG xt_HL xt_DSCP xt_CT xt_CLASSIFY usbserial usbnet usblp usbhid ums_usbat ums_sddr55 ums_sddr09 ums_karma ums_jumpshot ums_isd200 ums_freecom ums_datafab ums_cypress ums_alauda ts_kmp ts_fsm ts_bm thermal_sys pppox ppp_mppe ppp_async nf_reject_ipv4 nf_nat_tftp nf_nat_snmp_basic nf_nat_sip nf_nat_redirect nf_nat_proto_gre nf_nat_masquerade_ipv4 nf_nat_irc nf_nat_h323 nf_nat_ftp nf_nat nf_log_ipv4 nf_de
2019-05-18 09:19:58 notice kernel[]: nf_defrag_ipv4 nf_conntrack_tftp nf_conntrack_snmp nf_conntrack_sip nf_conntrack_rtcache nf_conntrack_proto_gre nf_conntrack_netlink nf_conntrack_irc nf_conntrack_h323 nf_conntrack_ftp nf_conntrack_broadcast mvsdio iptable_raw iptable_mangle iptable_filter ipt_ECN ip_tables hwmon hid_generic ebtables ebt_vlan ebt_stp ebt_redirect ebt_pkttype ebt_mark_m ebt_mark ebt_limit ebt_among ebt_802_3 crc_ccitt cdc_wdm ath9k_hw fuse sch_teql sch_tbf sch_sfq sch_red sch_prio sch_pie sch_netem sch_htb sch_gred sch_fq sch_dsmark sch_codel em_text em_nbyte em_meta em_cmp cls_basic act_vlan act_police act_pedit act_nat act_ipt act_gact act_csum act_bpf act_connmark nf_conntrack act_skbedit act_mirred em_u32 cls_u32 cls_tcindex cls_flow cls_route cls_fw sch_hfsc sch_ingress hid evdev ath10k_pci ath10k_core ath mac80211 cfg80211 compat ledtrig_usbdev ledtrig_oneshot xt_LED ledtrig_morse ledtrig_heartbeat ledtrig_gpio cryptodev xt_set ip_set_list_set ip_set_hash_netiface ip_set_hash_netport ip_set_hash_netnet ip_set_h
2019-05-18 09:19:58 notice kernel[]: ip_set_hash_netportnet ip_set_hash_mac ip_set_hash_ipportnet ip_set_hash_ipportip ip_set_hash_ipport ip_set_hash_ipmark ip_set_hash_ip ip_set_bitmap_port ip_set_bitmap_ipmac ip_set_bitmap_ip ip_set nfnetlink ip6t_REJECT nf_reject_ipv6 nf_log_ipv6 nf_log_common ip6table_raw ip6table_mangle ip6table_filter ip6_tables x_tables pppoatm ppp_generic slhc nfsd nfsv3 msdos ip_gre gre dummy sit ip6_tunnel tunnel6 tunnel4 ip_tunnel tun snd_compress snd_pcm_oss snd_mixer_oss snd_pcm snd_timer snd_rawmidi snd_seq_device snd_hwdep snd input_core soundcore rxkad vfat fat udf crc_itu_t ntfs nfs_layout_nfsv41_files nfsv4 nfs auth_rpcgss oid_registry lockd sunrpc grace minix isofs hfsplus hfs cramfs configfs cifs autofs4 kafs af_rxrpc dns_resolver dm_crypt dm_mirror dm_region_hash dm_log dm_mod br2684 atm multipath fscache raid456 async_raid6_recov async_pq async_xor async_memcpy async_tx raid10 raid1 raid0 linear md_mod nls_utf8 nls_koi8_r nls_cp1255 nls_iso8859_6 nls_iso8859_2 nls_iso8859_15 nls_iso8859_13 nls_iso88
2019-05-18 09:19:58 notice kernel[]: nls_cp932 nls_cp866 nls_cp864 nls_cp862 nls_cp852 nls_cp850 nls_cp775 nls_cp437 nls_cp1251 nls_cp1250 zram lz4_decompress lz4_compress zsmalloc xts algif_skcipher algif_hash af_alg sha512_generic sha256_generic sha1_generic seqiv jitterentropy_rng drbg pcbc md5 md4 marvell_cesa hmac gf128mul fcrypt ecb des_generic ctr cmac ccm cbc authenc xhci_plat_hcd xhci_pci xhci_hcd uhci_hcd ledtrig_transient ahci_platform uas xfs libcrc32c jfs f2fs exfat mii aead crypto_null [last unloaded: ifb]
2019-05-18 09:19:58 warning kernel[]: [76429.313865] CPU: 1 PID: 3129 Comm: syslog-ng Tainted: G W 4.4.178-7bc33afbb1b35f5830b2b1b42c9cd8a0-0 #1
2019-05-18 09:19:58 warning kernel[]: [76429.313868] Hardware name: Marvell Armada 380/385 (Device Tree)
2019-05-18 09:19:58 warning kernel[]: [76429.313870] Backtrace:
2019-05-18 09:19:58 warning kernel[]: [76429.313876] [<c001c504>] (dump_backtrace) from [<c001c744>] (show_stack+0x18/0x1c)
2019-05-18 09:19:58 warning kernel[]: [76429.313879] r6:00000000 r5:60000113 r4:c0770d28 r3:00000000
2019-05-18 09:19:58 warning kernel[]: [76429.313889] [<c001c72c>] (show_stack) from [<c02ffd7c>] (dump_stack+0x98/0xac)
2019-05-18 09:19:58 warning kernel[]: [76429.313896] [<c02ffce4>] (dump_stack) from [<c0029234>] (warn_slowpath_common+0x8c/0xbc)
2019-05-18 09:19:58 warning kernel[]: [76429.313899] r6:00000592 r5:bf8335c0 r4:00000000 r3:00000000
2019-05-18 09:19:58 warning kernel[]: [76429.313908] [<c00291a8>] (warn_slowpath_common) from [<c0029308>] (warn_slowpath_null+0x24/0x2c)
2019-05-18 09:19:58 warning kernel[]: [76429.313911] r8:d003e108 r7:00000002 r6:d003e3d0 r5:00000116 r4:10e9292a
2019-05-18 09:19:58 warning kernel[]: [76429.313929] [<c00292e4>] (warn_slowpath_null) from [<bf8335c0>] (hfsc_dequeue+0x34c/0x508 [sch_hfsc])
2019-05-18 09:19:58 warning kernel[]: [76429.313940] [<bf833274>] (hfsc_dequeue [sch_hfsc]) from [<c04ca07c>] (__qdisc_run+0x3c/0x1ac)
2019-05-18 09:19:58 warning kernel[]: [76429.313943] r9:00000040 r8:00000000 r7:00000000 r6:ea6ec800 r5:00000000 r4:d003e000
2019-05-18 09:19:58 warning kernel[]: [76429.313955] [<c04ca040>] (__qdisc_run) from [<c04a72cc>] (net_tx_action+0x150/0x180)
2019-05-18 09:19:58 warning kernel[]: [76429.313957] r10:00000000 r9:00000002 r8:c075c3c0 r7:00000000 r6:c075c3c0 r5:00000000
2019-05-18 09:19:58 warning kernel[]: [76429.313965] r4:d003e000
2019-05-18 09:19:58 warning kernel[]: [76429.313972] [<c04a717c>] (net_tx_action) from [<c002c7a8>] (__do_softirq+0x114/0x260)
2019-05-18 09:19:58 warning kernel[]: [76429.313975] r8:00000100 r7:e8c7a000 r6:40000002 r5:c0760080 r4:c0760088 r3:c04a717c
2019-05-18 09:19:58 warning kernel[]: [76429.313986] [<c002c694>] (__do_softirq) from [<c002cb80>] (irq_exit+0x80/0xb8)
2019-05-18 09:19:58 warning kernel[]: [76429.313989] r10:00000001 r9:f0803100 r8:ee808000 r7:00000001 r6:00000000 r5:00000000
2019-05-18 09:19:58 warning kernel[]: [76429.313997] r4:c0758ff0
2019-05-18 09:19:58 warning kernel[]: [76429.314003] [<c002cb00>] (irq_exit) from [<c0068b90>] (__handle_domain_irq+0x68/0xb8)
2019-05-18 09:19:58 warning kernel[]: [76429.314006] r4:c0758ff0 r3:c006cb4c
2019-05-18 09:19:58 warning kernel[]: [76429.314012] [<c0068b28>] (__handle_domain_irq) from [<c0009550>] (gic_handle_irq+0x50/0x94)
2019-05-18 09:19:58 warning kernel[]: [76429.314015] r8:e8c7bfb0 r7:f080210c r6:c0761038 r5:c077117c r4:f0802100 r3:e8c7bfb0
2019-05-18 09:19:58 warning kernel[]: [76429.314026] [<c0009500>] (gic_handle_irq) from [<c000a9b4>] (__irq_usr+0x54/0x80)
2019-05-18 09:19:58 warning kernel[]: [76429.314029] Exception stack(0xe8c7bfb0 to 0xe8c7bff8)
2019-05-18 09:19:58 warning kernel[]: [76429.314033] bfa0: 00000001 beb47d30 00000009 ffffffff
2019-05-18 09:19:58 warning kernel[]: [76429.314039] bfc0: 00000000 00000008 00000009 0000015a 00000003 00000000 00000001 beb47e04
2019-05-18 09:19:58 warning kernel[]: [76429.314044] bfe0: 00000000 beb47d08 b6ebc454 b6ebc420 60000010 ffffffff
2019-05-18 09:19:58 warning kernel[]: [76429.314046] r9:00000000 r8:10c5387d r7:10c5387d r6:ffffffff r5:60000010 r4:b6ebc420
2019-05-18 09:19:58 warning kernel[]: [76429.314055] ---[ end trace 7576d4853233204a ]---I know you are finishing with TO4 and you probably do not have the power 
!
I found a report on “QoS over Nftables” included in openWRT at: https://github.com/rosywrt/nft-qos with luci.
You plan to add the package ‘qos over nft’ to the TO4 or TO3? It seems that it is easier to set up, but not tested it!