Tens of thousands of patients were waiting for routine treatment at the Wye Valley Trust in October, new figures show.
It comes as Health and Social Care Secretary Wes Streeting warned there is still "a long way to go", despite waiting lists across England starting to fall.
NHS England figures show 24,416 patients were waiting for non-urgent elective operations or treatment at Wye Valley NHS Trust at the end of October – up slightly from 24,383 in September, and 23,039 in Oct-23.
Of those, 738 (3%) had been waiting for longer than a year.
The median waiting time from referral to treatment at the Wye Valley Trust was 15 weeks at the end of October – down from 16 weeks in September.
Nationally, 6.3 million people were waiting to start treatment at the end of October – in line with the end of September.
Tim Gardner, assistant director of policy at think tank the Health Foundation, said the figures show the substantial challenge the Government faces.
He said: "Whilst promising progress has been made in recent months, the 18-week target hasn’t been met for nearly a decade.
"With the NHS facing the prospect of a very difficult winter, making further headway over the next few months will be very tough."
Mr Gardner added once the winter is over the Government should focus on addressing inequalities in health across the country.
Separate figures show 1.6 million patients in England were waiting for a key diagnostic test in October – the same as in September.
At the Wye Valley Trust, 4,585 patients were waiting for one of 13 standard tests, such as an MRI scan, non-obstetric ultrasound or gastroscopy at this time.
Of them, 696 (15%) had been waiting for at least six weeks.
Other figures from NHS England show that 68 out of 96 cancer patients urgently referred to the Wye Valley Trust in October received treatment within two months of their referral.
A month previously – when 94 patients were referred – 72 were treated within 62 days.
In Oct-23, 47 out of 95 patients were treated within this period.
Danielle Jefferies, senior analyst at The King’s Fund, said the NHS is facing "a long list of priorities" across services, including reaching the 18-week waiting times target.
She added the way the NHS's performance is assessed should be reviewed to include a wider range of services and prompt reform.
Ms Jefferies said: "Winter pressures impact on all parts of the NHS and social care.
"How the health service is faring cannot just be measured by what is happening in hospitals — a true assessment must look at the care patients need from community and primary care services.
"Many people are struggling to access GP appointments and unable to get the support with social care services they need.
"There should be a more wide-ranging review of performance targets to shine a spotlight on these services and incentivise much-needed reform of the health service."
Health and Social Care Secretary Wes Streeting said: "Since the general election, we have been ramping up to delivering the extra two million appointments a year, ending the strikes and investing more in the health service.
"As a result, the NHS today is delivering a record number of treatments and waiting lists have begun to fall.
"There’s a long way to go, but through our plan for change we will get patients seen on time again."