Huawei HG553 ping drop

I have the router Huawei HG553 with openwrt v.18.06.7 installed. It works as router/nat to a wifi network. The performance are very low, if I try to ping an ip on Internet from my pc a lot of packets are lost. Usually 5 answered and 5 lost...
If I try to connect to the same wifi directly with my pc the network is strong.
The wifi signal is quite strong (82%). The configuration is almost by default, I have only added the wifi link to the provider. I don't believe that the router has not enough resources for this basic service.
Any idea?

Thank you in advance for your help.

Do you mean is a client of a wifi and you have your pc connected to hg553 lan?
Hg553 have a strong signal but also a strip antenna printed on pcb ..... could be a issue due by distance from access point?

Yes, my PC is cable connected to one LAN port of hg553.

The hg553 is a client of a wifi network and should work ad gateway of his lan, but is very low. The access point is not so far from the hg553 (the signal is around 80%)

Thanks a lot.

According to what you said you don't use relayd so your lan ip class is different from that of wifi

With a pc in your lan ping:
The ip of your router
The ip of the external access point
The ip of Google that is
The site
You'll obviously have different responses
The first the fastest, but compared this the second should show the quality of wifi client connection
The third should be affected by delays of first
plus second
plus the delay of remote AP connection trough internet provider that is out of the scope of your managing possibility.
The fourth is like the third plus an initial delay due to dns
So if you can point to the page of that remote AP with your browser and have a relative speedness it means you are ok (But ping results are the real measure).