  We investigate lattice Weinberg - Salam model without fermions numerically
for the realistic choice of coupling constants correspondent to the value of
the Weinberg angle $\theta_W \sim 30^o$, and bare fine structure constant
around $\alpha \sim 1/150$. We consider the values of the scalar self coupling
corresponding to Higgs mass $M_H \sim 100, 150, 270$ GeV. It has been found
that nonperturbative effects become important while approaching continuum
physics within the lattice model. When the ultraviolet cutoff $\Lambda =
\frac{\pi}{a}$ (where $a$ is the lattice spacing) is increased and achieves the
value around 1 TeV one encounters the fluctuational region (on the phase
diagram of the lattice model), where the fluctuations of the scalar field
become strong. The classical Nambu monopole can be considered as an embryo of
the unphysical symmetric phase within the physical phase. In the fluctuational
region quantum Nambu monopoles are dense and, therefore, the use of the
perturbation expansion around trivial vacuum in this region is limited. Further
increase of the cutoff is accompanied by a transition to the region of the
phase diagram, where the scalar field is not condensed (this happens at the
value of $\Lambda$ around 1.4 TeV for the considered lattice sizes). Within
this region further increase of the cutoff is possible although we do not
observe this in details due to the strong fluctuations of the gauge boson
correlator. Both mentioned above regions look unphysical. Therefore we come to
the conclusion that the maximal value of the cutoff admitted within lattice
Electroweak theory cannot exceed the value of the order of 1 TeV.
