Wireless connections are susceptible to interference, any metals, or objects will obstruct the signal coming from your router. On the other hand, a wired connection will give you more reliability because it is directly connected to the router.
Kung mag tetest ka ng wifi speed sa both pc and mobile make sure, magkalapit at walang objects na makaka interfere sa signals ng wifi.
Make sure din na yung wifi chip ng phone mo is not inferior sa wifi chip ng pc mo, or vice versa. Kung luma naman yung wifi chip ng either of the devices baka don yung issue kasi nga luma at mas mabagal yung chip.