Welcome to this user forum.
It would help if you could tell forum members which TP Link VDSL modem/router you are using.
The usual problem is that people forget that the default gateway on TP Link routers is 192.168.1.1 and not 192.168.1.254 like the home hub.
So check the laptop and PC settings, as that would also explain why you cannot get to the router setup page. They should be set to get the IP address and DNS servers automatically using DHCP.
I use that router, and have no issues connecting to any devices, so it must be an issue with the settings on the laptop and PC.
If you look at the network status on the laptop, it should tell you what IP address and DNS servers it is using.
You can also look at the DHCP server clients list on the router, and see if its been allocated an IP address.
The fact that other devices are working, would indicate it has to be an issue with the laptop and PC wireless settings. Can you see then showing on the wireless status page of the router?
What OS are they running?
As they work with Ethernet, it has to be a wireless issue. Remember Windows uses different settings for wireless and Ethernet.
This suggestion by forum member gg30340, may fix the problem.
Left click on Internet Protocol IPV4, click on properties. Check the options to obtain IP address and DNS Server address automatically.
The IP address issued by DHCP, should be in the range 192.168.1.100 to 192.168.1.199.
My daughter is using the same router, with 32 devices connected, using thse wireless settings, if its any help, just in case you have some wireless card compatibility issues?
What sort of wireless signal level are you seeing as it looks more like possible wireless interference or poor signal level.
Also it may be downloading Windows updates, which will make it appear to be running slowly.
If it is downloading updates, then it may be better to leave it connected via Ethernet, until the downloads finish.