Web client not showing remote machines while connected through range extender

[ViTe]

Linux Mint, Web client 8.5.5, latest Chrome or Firefox, DLink DAP-1530 Range Extender.

I have a bit poor WiFi signal near one of the machines and tried WiFi Range Extender.
Client works fine while machine connected to a router with USB Wifi Dingle.
If connected though extended network it says "API Error: Type Error: Failed to fetch" and not showing other machines.
Range extender has LAN port and I tried to connect through that LAN port. Same result: API Error: Type Error: Failed to fetch
Other sites works fine through range extender.

Any ideas?

[calxalot]

Is IPv4 enabled?