My ISP recently replaced my router with one that doesn't support setting the DNS server so I now have to use the DHCP server workaround. My new router also doesn't allow disabling its DHCP server, but I was able to get around that by setting the IP address range to just my Pi-Hole's IP and then excluding that IP from the range in my Pi-Hole's DHCP server.
This mostly got my Pi-Hole setup back to working as it used to, but I'm noticing an issue where sometimes the internet speed of one of my devices will slow down to a crawl for many minutes to the point it's almost unusable. This only affects one specific device: a Windows 11 laptop. None of my other devices (e.g. Macbook Pro, Android phone, Samsung smart TV) have experienced this issue. The issue occurs multiple times a day, and I tested going back to using my router's DHCP server for a day and didn't experience the issue at all in that time frame.
Expected Behaviour:
The internet speeds should be stable on all devices after enabling the Pi-Hole's DHCP server.
Actual Behaviour:
The internet speeds on my Windows 11 laptop randomly degrade for a couple minutes multiple times per day while all other devices are unaffected. I ran a speed test on my Windows 11 laptop and Macbook Pro side-by-side during one of these occurrences and the results were ~50Mbps on the Windows laptop and ~400Mbps on the Macbook.