Strange Networking problem

At my daughter's business, they have a network of about 6 computers and other devices. They each have fixed IP adresses on the network using a hosts file (this is necessary because some of the proprietary devices on the network come with fixed/hardwired IP addresses)

Everything worked fine until recently when the motherboard of one of the computers failed. We replaced the computer and swapped the system HDD from the failed computer to the replacement. This worked fine until we tried to put it on the network.

As usual, I changed the network adapter IPV4 settings to reflect this computer's intended IP address

IP Address: 192.168.1.98
Subnet Mask: 255.255.255.0
Default Gateway: 192.168.1.1

Note. We also use Cloudflare DNS so I set this accordingly

Preferred DNS Server: 1.1.1.1
Alternate DNS Server: 1.0.0.1

However, when I do all this, the computer connects to the network fine, but will not connect to the internet. When I run the Windows 10 troubleshooter, it reports that "DHCP is not enabled for Ethernet 2". I allow the troubleshooter to apply the fix, and now the internet works, but the computer drops off the network. To summarize

When IPV4 for is set to a fixed IP address: The network is OK but no Internet.
When IPV4 is set to obtain IP address automatically: The internet is OK, but no network.

I feel this is either a configuration problem or a driver issue. The two computers involved are both HP Compaq Elite 8200 models, but the motherboards do look slightly different, so it is possible there are some minor hardware differences. I did try updating the network adapter drivers but it said it 'already has the latest drivers for this device' (I think Windows updated all the drivers when I first booted up the computer after installing the system HDD.

Anyone have any ideas why this might be happening?

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