I set this up a few days ago and thought it was all working OK.

Then my Oppo started having issues not connecting to the network.

I just looked into this and found that it was trying to use one of the reserved IPs I had set for another device (none had been set for the Oppo).

Not sure how this can happen, as I thought the point of reserving an IP was that it would only be used on the device who's MAC address is stored against it?

One thought: is it a coincidence that the IP address for my BDP-105 ends in .105? I.e. did Oppo set a static IP ending in 105, or something??

Otherwise, anything else I can do to troubleshoot this?

I've temporarily set the Oppo to the 105 reserved address and will see if that helps...

HC: 861v4/ID40/LPS, DSP5000, DSP5000VC, DSP3100, SW1600, HD621, Oppo BDP-105, Sony VPL-HW55ES
2-Channel: Oppo BDP-105, TEAC VRDS-7/Trichord Clock 3/PSU, 551, Quad 303, Harbeth Compact 7ES-3, Kimber cables, Russ Andrews mains and supports.
Previous Meridian: 5000C, 5200SL, 7200.2, 6000, 562V.2, 568.2mm, 800v4, 808.2i, 818v2/v3, 861v8, 502