The technician is unable to access the company portal website, but other websites work fine. This suggests an issue with resolving the specific URL of the company portal, which is a function of DNS.
Here's why other options are not the most likely cause:
DHCP reservations: This is not relevant as the issue persists even when the technician tries a different workstation, indicating a problem beyond individual device configuration.
Static IP addresses: Similar to DHCP reservations, static IPs are not likely the cause as both affected workstations are experiencing the issue.
Default gateway: While the default gateway is necessary for internet access, other websites are working, making it less likely to be the root cause.
Reference:
CompTIA A+ Certification Core 1 220-1101 Study Guide, Chapter 4: Networking, Section 4.2 Addressing and Naming

Domain Name System (DNS) is an Internet service that translates domain names (e.g., its.umich.edu) into IP addresses. Dynamic Host Configuration Protocol (DHCP) is a protocol for automatically assigning IP addresses and other configurations to devices when they connect to a network.

Thunderbolt cables are commonly used to connect Apple laptops to external displays or other devices. While Thunderbolt is available on some Windows and Chromebook devices, it is most commonly associated with Apple products. Reference: https://www.intel.com/content/www/us/en/products/docs/io/thunderbolt/thunderbolt-technology-general.html

Explanation
A blot on the screen of a smartphone is most likely caused by damage to the digitizer, which is the part of the device responsible for interpreting touch input. Improper charging is unlikely to cause a blot on the screen, as is damage to the ambient light sensor. Liquid damage is a possibility, but it is more likely to cause discoloration or other physical damage to the screen.