I moved from Virgin Media to Open FIbre a few months ago. As part of the move VM's Hub4 was replaced with a TP-Link EX230v. Since the majority of the wired devices at home are connected via a 16-port switch, it was as simple as disconnecting the VM box and connecting the OF one. My main PC was different as I connected it straight to the router to reduce ping and achieve a more stable connection.

However, we have a strange issue: Whenever I shut down my main PC or laptop, the internet connection is lost and we can't get back on for up to ten minutes. We've recently discovered that browsing the internet from my phone (wirelessly via a range extender) is enough to bring the connection back up and we can continue. I tried connecting my PC to the switch instead but this makes no difference. The laptop is connected over wifi.

All devices on the network use 192.168.0.1 for DHCP, and the only other thing of note is that both my PC and laptop run Apache for dev work. I don't host any public sites on them, so nothing is allowed in through the router. 

Does anyone have any suggestions on how to fix this, or where I should look for further clues?