Even for future proofing as fibre optical digial cable is the modern future proofing option if deciding to spend more than this. They're impossible to fit RJ12 plugs so they use fakes with strandsinstead of solid wiring like mine!
eBay
Vention Ethernet Cable Cat 7 Lan Cable STP RJ45 Network Cable for Compatible Patch Cord for Computer Router Laptop Flat-Wire 20M
Aliexpress UK
This cable can be used to connect your ADSL Modem (with an RJ11socket) to the Filter/Splitter. plugged into your BT ADSL enabled wall socket. Connection: 4 Pin RJ11 to RJ11. Suite for ADSL connection.
eBay
Vention Ethernet Cable Cat 6 Network Cable 4 Twisted Pair Patch Cord Internet UTP Cat6 Lan Cable for Laptop Router Ethernet RJ45
Aliexpress UK
High Quality 4 Pin RJ11 US to RJ11 US ADSL Cable. This cable can be used to connect your ADSL Modem (with an RJ11socket) to the Filter/Splitter plugged into your BT ADSL enabled wall socket. Connection: 4 Pin RJ11 to RJ11.
eBay
5pcs/Lot Ethernet Cable 0.2m/0.3m/0.5m/1m Cat6 UTP Wire Cable RJ45 Network Cable Patch Cord for Router Laptop
Aliexpress UK
This cable can be used anywhere a 2 or 4 pin RJ11 connection is required but are most commonly used to connect your ADSL Modem (with an RJ11 socket) -. to the Filter/Splitter plugged into your BT ADSL enabled wall socket.
eBay
Network Cable Super Five Types Finished CAT5 Network Cable RJ45 Network Cable Computer Router Switch Cable 1m 2m 3m 5m
Aliexpress UK
Fitted with standard BT style 6 way plug (631A) and RJ12 plug (6P6C). Connector type B - RJ12 Plug. Connector type A - BT Plug 631 A. Straight wired modem leads.
eBay
Vention Cat7 Ethernet Cable RJ45 Gigabit Network Lan Cable rj45 Patch Cord 1m2m3m4m5m10m40m for PC Router Laptop Cable Ethernet
Aliexpress UK
Connection: 4 Pin RJ11 to RJ11. The RJ11 4 Pins are gold platted and 100% pure Copper used In order to avoid losing the data. plugged into your BT ADSL enabled wall socket. The plastic of this cable is made of PVC and is 4pin cable in order to keep the data quality flow more.
eBay
CAT7 Ethernet Cable 10Gb RJ45 Lan Network Cable Networking Ethernet Patch Cord CAT 7 Network Cable For Computer Router Laptop
Aliexpress UK
This cable can be used to connect your ADSL Modem (with an RJ11 socket) to the Filter/Splitter plugged into your BT ADSL enabled wall socket. RETRACTABLE ADSL CABLE 240CM. RJ-11 to RJ-11on both sides.
eBay
CAT7 Ethernet Cable 10Gb RJ45 Lan Network Cable Networking Ethernet Patch Cord CAT 7 Network Cable For Computer Router Laptop
Aliexpress UK
This cable can be used to connect your ADSL Modem (with an RJ11socket) to the Filter/Splitter. plugged into your BT ADSL enabled wall socket. Connection: 4 Pin RJ11 to RJ11. Suite for ADSL connection.
eBay
Cat6 Ethernet Cable Flat Lan Cord UTP Network Patch Cable RJ45 for PS5 PC IPTV Xbox Internet Router Cat 6 Internet Cable
Aliexpress UK