When I reseated the LAN cable, I could only connect to some sites.

Assumptions/What you want to realize
I changed the LAN cable from the broadband router to the router and the LAN cable from the broadband router to the PC.
Then, I could only connect to a part of the site.
How can I connect to the Internet?

↓ Specific situation ↓

<Purpose of changing cables>
To increase line speed

<Equipment in use>
Modem→NTT
Broadband Router→WBC V130(NTT)
Router→Buffalo Changed LAN cable → https://www.elecom.co.jp/products/LD-GF2BU2.html

<Connectivity>
Modem=Broadband Router=WiFi Router=WiFi
Modem = Broadband Router = Wired LAN Cable to PC
(Modems and broadband routers are written separately.)

<Status>
PC connected via wired LAN → site connected and site not connected has been created.(Regardless of browser cache)
WIFI Connected PC → No Internet Connection / Secure Internet Not Available

<Steps to change>
①Power Off the Router and Modem (Unplugging the Cord)
②Unplug the "Broadband Router ルータ ルータ " ル PC "ーター LAN LAN を 有線 有線 の⇔ " 上記⇔ に"
③Wait about 15 minutes
④Turn on both equipment
⑤<Conditions> above
⑥Try the reverse of the above steps (replacing the original cable)
⑥WiFi is normal, but wired PC remains the same
⑥First, change the LAN cable between the broadband router and the PC
⑨The wired PC is still in the same state as <Status>
⑩Now you notice that only the new PC is showing WiFi at 5GHz

- It's like this now -

Please reply.