An odd one if you'll bear with me. Last night I went on the BT router (HH5A) admin pages - Home Network. It was it always was - all devices connected as normal with the familiar IP addresses, except my son's PC (ethernet LAN) was not listed. I shouted upstairs to him and he was definitely on line playing Minecraft. I got him to run ipconfig and his IP address was 192.168.1.53. I pinged it OK from another PC, but still didn't show on the HH5A. The DHCP allocation range was default and 192.168.1.53 is outside that range - odd. He stopped playing Minecraft and returned to desktop and DHCP immediately allocated 192.168.1.69 to it, which is the IP address always used by my son's PC. Minecraft was restarted and it stayed at 192.168.1.69.
I questioned if he was running a server or doing anything out of the ordinary and he was adamant he wasn't doing anything different, so I'm a bit confused. Any ideas?