Mesh setup - slow download speed

I have a mesh setup like below
Omada EAp245 (original firmware)->TPLink Archer C7 (Openwrt) -> TPLink Archer C5 (Openwrt). The Archer C7 has been connected as AP from EAP245 and mesh has been configured. The connectivity between C7 & C5 is good, but the client connected to C5, is having very slow download speed using speedtest (less than 1mbps) where as the upload is good around 40mbps. Anything needs to be tuned?