What the heck are they on about? I wouldn't EVER expect an actual WAN connection to end in .1 or .254
Bad news - about 1 in 128 of all broadband client WAN IPv4 addresses end in .1 or .254. Indeed .0 and .255 account for another 1 in 128 - ish.
Name: cpc114124-lee213-2-0-cust255.7-1.cable.virginm.net
Address: 86.28.209.0
Pinging 86.28.209.0 with 32 bytes of data:
Reply from 86.28.209.0: bytes=32 time=35ms TTL=52
Reply from 86.28.209.0: bytes=32 time=36ms TTL=52
Name: cpc114124-lee213-2-0-cust510.7-1.cable.virginm.net
Address: 86.28.209.255
Pinging 86.28.209.255 with 32 bytes of data:
Reply from 86.28.209.255: bytes=32 time=25ms TTL=53
Reply from 86.28.209.255: bytes=32 time=24ms TTL=53
Name: 51-148-174-1.dsl.in-addr.zen.co.uk
Address: 51.148.174.1
Pinging 51.148.174.1 with 32 bytes of data:
Reply from 51.148.174.1: bytes=32 time=16ms TTL=58
Reply from 51.148.174.1: bytes=32 time=16ms TTL=58
Etc.
Default gateways rarer as there are far fewer required but it happens, especially on networks using IPoE or straight DHCP where there are smaller IP pools than those you'd find via PPP.
Perhaps CarlT will offer an opinion?
I haven't a clue what they're waffling on about if I'm honest. If there's supposed to be a VLAN tag there, or there's an incorrect VLAN tag, it doesn't work full stop, it's not intermittent. None of my services expose a VLAN tag to my router so I'm totally lost to be honest. VLAN tags are placed on the traffic by my ONT/U, much as they are by Openreach modems as far as I'm aware.
A reminder neither the ONTs or modems are actually modems, they are bridges. Bridges can do things like apply VLAN tags. Only time VLAN tags need to be configured are when your own kit is being plugged straight into the copper line rather than a, pre-configured, Openreach modem.