wlan1 (2GHz) slower than wlan2 (5GHz)

I’m using wAP ac configured as bridge mode WISP AP. Ethernet port is connected to router. It works fine over 5GHZ wlan2 interface while over wlan1 (2GHz) works much much slower which is very incovenient for me since we use devices with 2GHz wi-fi adapter. What did i miss?

Many thanks and my appologies if i misplaced this post.

By default 5ghz was introduced in soho routers because of better performance.
So if you get 200mbps in 5ghz and 50mbps in 2ghz it could be a fair result. Now it depends what does “much much slower” means for you.
Also if I use a tplink wireless adapter at my house I get a speed of ~30mbps. In the same computer, the same position, with intel card I get over 70mbps. Both are 2x2 mimo, 300mbps.