Connectivity issues to SAP SQL Anywhere database as a secondary database with Django

Question

I can connect to a SAP SQL Anywhere database with FreeTDS and pyodbc as follows:

# hello_sybase.py

import pyodbc

try:
    con = pyodbc.connect('Driver={FreeTDS};'
            'Server=10.60.1.6,2638;'
                      'Database=blabla;'
                      'uid=blabla;pwd=blabla')
    cur = con.cursor()
    cur.execute("Select * from Test")
    for row in cur.fetchall():
        print (row)
    cur.close()
    con.close()
except Exception as e:
    print(str(e))

I tried to connect in a Django view as follows:

import pyodbc

CONN_STRING = 'Driver={FreeTDS};Server=10.60.1.6,2638;Database=blabla;uid=blabla;pwd=blabla'


def my_view(request):
    with pyodbc.connect(CONN_STRING) as conn:
        cur = conn.cursor()
        cur.execute('SELECT * FROM test')
        rows = list(cur.fetchall())
    return render(request, 'my_template.html', {'rows': rows})

When I run python manage.py runserver and run the code in the above view.

I have this error message '08001', '[08001] [FreeTDS][SQL Server]Unable to connect to data source (0) (SQLDriverConnect)')

I tried to put TDS_Version=7.4 as was mentioned here in the comment, but it didn't helped.

Is it possible that these are issues with the threading as is said in that comment?

How can I fix it? The code works without Django, but with python manage.py runserver it doesn't work.

To be more precise, I use this code snippet in the view

if second_form.is_valid():
            try:
                con = pyodbc.connect(CONN_STRING)
                con.setdecoding(pyodbc.SQL_CHAR, encoding='cp1252')
                con.setdecoding(pyodbc.SQL_WCHAR, encoding='cp1252')
                con.setencoding(encoding='cp1252')
                cur = con.cursor()
                cur.execute("Select * from test")
                result2 = list(cur.fetchall())
                print(results2)
                cur.close()
                con.close()
                context['result2'] = result2
                context['form2'] = SecondForm(request.POST)
            except Exception as e:
                print (str(e))

Here is about the error message

This SQLSTATE is returned for one or more of the following reasons:

Db2 ODBC is not able to establish a connection with the data source.
The connection request is rejected because a connection that was established with embedded SQL already exists.

Is it problem with my FreeTDS version? How can I safely upgrade it on Ubuntu 18.04?