The usual culprits are structural: no clear statement of who the site serves, no proof, a contact page as the only conversion path, invisible pricing signals, and content about the company instead of the customer's problem. Each fix is unglamorous and each one moves enquiries.
A B2B site fails silently when a qualified visitor cannot answer three questions in ten seconds: is this for someone like me, can they actually do it, and what happens if I reach out. Most sites answer none of them above the fold.
Proof is the multiplier. Named clients, real numbers, specific outcomes. In their absence every claim on the page reads as decoration, because it is.
Five moves, in order
State plainly who you serve and what changes for them. Put evidence near every claim. Offer a low-commitment first step, an audit, a scoping call, not just a contact form. Signal your price band so wrong-fit visitors filter themselves. Write service pages around the buyer's problem, with your process as the supporting cast.
Then instrument it: if you cannot see which pages produce enquiries, you cannot improve any of them.