I came across a way to get the uptime of a BT Home Hub very easily which is useful given the device does not support SNMP.
- platform: scrape
name: 'BTHomeHub5'
resource: http://192.168.1.254/nonAuth/wan_conn.xml
select: 'sysuptime'
attribute: 'value'
The returned sensor Up time is in seconds and I then use a template sensor to convert to days/hours/mins. I suspect there is additional useful information that can be pulled off the device in a similar manner.