REIN, or R
oise to give it its full & fancy name is one of the biggest bug bears of broadband. In short this is interference on the telephone line that affects the broad band speed &/or stability. It can be caused by numerous things, from nearby transmitters to street lights & flashing Christmas lights!
The good news is there are a couple of devices that can be fitted to try & combat this. First off it the BT 80BRF3 :-
This small device is fitted upstream of the master socket, screw terminals connect to the incoming line & IDC terminals connect to the cable that feeds the master socket. The RF filter cuts out the radio interference which in turn improves broadband speed & stability.
The second device that can fix this problem is the BT VDSL faceplate :-
This is a filtered faceplate that is compatible with ADSL & VDSL, it features a filter similar to the 80B RF3 to combat REIN but also features full ADSL/VDSL filtering (so no need for ugly plug in filters!).
The BT MK3 VDSL faceplate is considered the best filtered faceplate currently available. Unlike the 80B RF3 solution no re-wiring is required, the faceplate simply slots onto the NTE5A master socket (also available, https://www.run-it-direct.co.uk/bt-line-boxes-and-sockets/openreach-branded-nte5-master-socket/
In severe cases BT Openreach state BOTH devices can be fitted to a line, it should be noted however that this can result in reduced sync speed.