TP-LINK TD-W8970 Vdsl Connection Issue


I have two different brand modems (TP-LINK TD-W8970 and Zyxel P-2812HNUL-F1) that running OpenWRT(19.07.8) and the modems don't work with a stable DSL connection and the line was losing a few days later.

Also, I used another modem(TP-LINK TD-W9970 v3 default rom) on the same line and I didn't lose connection with it in ten days.

There is below my network file code. Could you please check it someone? Is there have any missing or wrong code ?

config interface 'loopback'
	option ifname 'lo'
	option proto 'static'
	option ipaddr ''
	option netmask ''

config globals 'globals'
	option ula_prefix 'fd62:394a:c834::/48'

config interface 'wan'
	option ifname 'dsl0.35'
	option proto 'pppoe'
	option ipv6 '1'
	option username '*********comnet@comnet'
	option password '**********'

config atm-bridge 'atm'
	option encaps 'llc'
	option payload 'bridged'
	option nameprefix 'dsl'
	option vci '35'
	option vpi '8'

config dsl 'dsl'
	option firmware '/lib/firmware/vdsl.bin'
	option annex 'b'
	option line_mode 'vdsl'
	option tone 'bv'
	option xfer_mode 'ptm'
	option ds_snr_offset '0'

config interface 'lan'
	option type 'bridge'
	option ifname 'eth0.1'
	option proto 'static'
	option ipaddr ''
	option netmask ''
	list dns ''
	list dns ''
	option delegate '0'

config device 'wan_dsl0_dev'
	option name 'dsl0'
	option macaddr '14:cc:20:c5:18:2b'

config switch
	option name 'switch0'
	option reset '1'
	option enable_vlan '1'

config switch_vlan
	option device 'switch0'
	option vlan '1'
	option ports '0 2 4 5 6t'

"unstable" can mean many things with a DSL connection - can you be more descriptive about the symptoms?

Your upstream data rate is very low given the reported noise margin - what speeds does your ISP say you should get? Even your downstream noise margin is a bit higher than would normally be expected (6-6.5dB). For comparison, what connection information does your TD-W9970v3 give?

You might want to consider adding a hotplug script to log DSL status changes which might help with diagnosing any problems.

Are you using the xDSL modem firmware "blob" distributed with OpenWrt images or have you installed an alternative one? You might want to check this thread and consider testing alternative xDSL firmwares.

As your VDSL connection doesn't appear to require vectoring support, the updates and fixes to this functionality in OpenWrt 22.03 aren't likely to help but you might consider trying it out anyway and pick up the security and other fixes. You can use a vectoring capable xDSL firmware on a non-vectoring connection, so running 22.03 would also give you a wider selection of alternative versions to evaluate.