unstable connection when to use LTE modems

I am using ADSL to connect to internet it works good. but when I am using LTE modem cause to timeout connection even though when speed is good or idle for make connection. I changed modem place and it works good but with low signal and also with internet connection wiznet can not connect to host!. at the same time I made a connection to host with Google Chrome and connection has established but wiznet does not! how can I make connection as well as computer?
I use LWIP tcp stack with LPC1768 to test internet speed. it works and connection established immediately. but at the same time wiznet does not!

It is not possible to answer your question without looking into troubleshooting data. Would you please make Wireshark log showing how W5500 can not connect to the host?
Your W5500 driver also makes difference here - how does it behave when it can not establish connection to the remote host? Does it try to reopen socket/reconnect?